Improve typing for under_cached_property decorator

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 90.90909% with 2 lines in your changes missing coverage. Please review.

Project coverage is 88.27%. Comparing base (825020d) to head (9194479). Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
src/propcache/_helpers_py.py	90.90%	0 Missing and 2 partials :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #38 +/- ## ========================================== - Coverage 88.38% 88.27% -0.11% ========================================== Files 17 17 Lines 680 691 +11 Branches 63 67 +4 ========================================== + Hits 601 610 +9 Misses 63 63 - Partials 16 18 +2 ``` | [Flag](https://app.codecov.io/gh/aio-libs/propcache/pull/38/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=aio-libs) | Coverage Δ | | |---|---|---| | [CI-GHA](https://app.codecov.io/gh/aio-libs/propcache/pull/38/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=aio-libs) | `88.27% <90.90%> (-0.11%)` | :arrow_down: | | [MyPy](https://app.codecov.io/gh/aio-libs/propcache/pull/38/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=aio-libs) | `72.31% <59.09%> (+0.05%)` | :arrow_up: | | [OS-Linux](https://app.codecov.io/gh/aio-libs/propcache/pull/38/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=aio-libs) | `98.37% <92.30%> (-0.32%)` | :arrow_down: | | [OS-Windows](https://app.codecov.io/gh/aio-libs/propcache/pull/38/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=aio-libs) | `93.60% <92.30%> (-0.34%)` | :arrow_down: | | [OS-macOS](https://app.codecov.io/gh/aio-libs/propcache/pull/38/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=aio-libs) | `94.13% <92.30%> (-0.29%)` | :arrow_down: | | [Py-3.10.11](https://app.codecov.io/gh/aio-libs/propcache/pull/38/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=aio-libs) | `92.83% <84.61%> (-0.61%)` | :arrow_down: | | [Py-3.10.15](https://app.codecov.io/gh/aio-libs/propcache/pull/38/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=aio-libs) | `95.43% <84.61%> (-0.63%)` | :arrow_down: | | [Py-3.11.10](https://app.codecov.io/gh/aio-libs/propcache/pull/38/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=aio-libs) | `95.43% <84.61%> (-0.63%)` | :arrow_down: | | [Py-3.11.9](https://app.codecov.io/gh/aio-libs/propcache/pull/38/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=aio-libs) | `92.83% <84.61%> (-0.61%)` | :arrow_down: | | [Py-3.12.6](https://app.codecov.io/gh/aio-libs/propcache/pull/38/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=aio-libs) | `95.43% <84.61%> (-0.63%)` | :arrow_down: | | [Py-3.13.0-rc.3](https://app.codecov.io/gh/aio-libs/propcache/pull/38/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=aio-libs) | `95.43% <84.61%> (-0.63%)` | :arrow_down: | | [Py-3.8.10](https://app.codecov.io/gh/aio-libs/propcache/pull/38/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=aio-libs) | `93.13% <84.61%> (-0.62%)` | :arrow_down: | | [Py-3.8.18](https://app.codecov.io/gh/aio-libs/propcache/pull/38/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=aio-libs) | `95.75% <84.61%> (-0.63%)` | :arrow_down: | | [Py-3.9.13](https://app.codecov.io/gh/aio-libs/propcache/pull/38/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=aio-libs) | `92.81% <84.61%> (-0.62%)` | :arrow_down: | | [Py-3.9.20](https://app.codecov.io/gh/aio-libs/propcache/pull/38/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=aio-libs) | `95.42% <84.61%> (-0.63%)` | :arrow_down: | | [Py-pypy7.3.11](https://app.codecov.io/gh/aio-libs/propcache/pull/38/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=aio-libs) | `95.47% <84.61%> (-0.73%)` | :arrow_down: | | [Py-pypy7.3.16](https://app.codecov.io/gh/aio-libs/propcache/pull/38/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=aio-libs) | `95.09% <84.61%> (-0.73%)` | :arrow_down: | | [Py-pypy7.3.17](https://app.codecov.io/gh/aio-libs/propcache/pull/38/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=aio-libs) | `95.11% <84.61%> (-0.73%)` | :arrow_down: | | [VM-macos-latest](https://app.codecov.io/gh/aio-libs/propcache/pull/38/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=aio-libs) | `94.13% <92.30%> (-0.29%)` | :arrow_down: | | [VM-ubuntu-latest](https://app.codecov.io/gh/aio-libs/propcache/pull/38/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=aio-libs) | `98.37% <92.30%> (-0.32%)` | :arrow_down: | | [VM-windows-latest](https://app.codecov.io/gh/aio-libs/propcache/pull/38/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=aio-libs) | `93.60% <92.30%> (-0.34%)` | :arrow_down: | | [pytest](https://app.codecov.io/gh/aio-libs/propcache/pull/38/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=aio-libs) | `98.37% <92.30%> (-0.32%)` | :arrow_down: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=aio-libs#carryforward-flags-in-the-pull-request-comment) to find out more.

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