dev(narugo): add thread-safe cache

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 96.87%. Comparing base (c1bca12) to head (7a8c434). Report is 7 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #121 +/- ## ========================================== + Coverage 96.86% 96.87% +0.01% ========================================== Files 105 106 +1 Lines 3441 3456 +15 ========================================== + Hits 3333 3348 +15 Misses 108 108 ``` | [Flag](https://app.codecov.io/gh/deepghs/imgutils/pull/121/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=deepghs) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/deepghs/imgutils/pull/121/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=deepghs) | `96.87% <100.00%> (+0.01%)` | :arrow_up: | 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=deepghs#carryforward-flags-in-the-pull-request-comment) to find out more.

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