refactor: remove dependency on pytz

[codecov[bot]]

Codecov Report

Patch coverage: 100.00% and project coverage change: -0.05% :warning:

Comparison is base (0184fe7) 79.26% compared to head (4587e1e) 79.22%. Report is 1 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #90 +/- ## ========================================== - Coverage 79.26% 79.22% -0.05% ========================================== Files 6 6 Lines 492 491 -1 Branches 73 73 ========================================== - Hits 390 389 -1 Misses 80 80 Partials 22 22 ``` | [Files Changed](https://app.codecov.io/gh/Bluetooth-Devices/bthome-ble/pull/90?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Bluetooth-Devices) | Coverage Δ | | |---|---|---| | [src/bthome\_ble/\_\_init\_\_.py](https://app.codecov.io/gh/Bluetooth-Devices/bthome-ble/pull/90?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Bluetooth-Devices#diff-c3JjL2J0aG9tZV9ibGUvX19pbml0X18ucHk=) | `100.00% <100.00%> (ø)` | | | [src/bthome\_ble/parser.py](https://app.codecov.io/gh/Bluetooth-Devices/bthome-ble/pull/90?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Bluetooth-Devices#diff-c3JjL2J0aG9tZV9ibGUvcGFyc2VyLnB5) | `85.62% <100.00%> (-0.05%)` | :arrow_down: |

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[bdraco]

Thanks @scop