ci: update release please to new GHA

[gruebel]

This PR

• the google-github-actions/release-please-action GHA was deprecated and this the replacement 🙂
• also added the version.py file, which hopefully will get updated correctly with the SDK version and can be used by 3rd parties

Related Issues

Fixes #332

[codecov[bot]]

Codecov Report

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

Project coverage is 97.41%. Comparing base (44b0787) to head (16481d0).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #340 +/- ## ======================================= Coverage 97.41% 97.41% ======================================= Files 26 26 Lines 1240 1240 ======================================= Hits 1208 1208 Misses 32 32 ``` | [Flag](https://app.codecov.io/gh/open-feature/python-sdk/pull/340/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=open-feature) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/open-feature/python-sdk/pull/340/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=open-feature) | `97.41% <ø> (ø)` | | 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=open-feature#carryforward-flags-in-the-pull-request-comment) to find out more.

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