Devops: update the continuous deployment workflow

[sphuber]

Various fixes and updates after adopting PEP 621

• Use flit to build and upload to PyPI
• Use string for Python version numbers instead of floats
• Install package with pre-commit extra for pre-commit step
• Make the tag filter regex more specific to match vx.y.z
• Add an explicit check to ensure tag and package version match

[codecov[bot]]

Codecov Report

Base: 89.54% // Head: 89.54% // No change to project coverage :thumbsup:

Coverage data is based on head (8653e3a) compared to base (8653e3a). Patch has no changes to coverable lines.

:exclamation: Current head 8653e3a differs from pull request most recent head 9e74e21. Consider uploading reports for the commit 9e74e21 to get more accurate results

Additional details and impacted files

```diff @@ Coverage Diff @@ ## develop #121 +/- ## ======================================== Coverage 89.54% 89.54% ======================================== Files 15 15 Lines 1137 1137 ======================================== Hits 1018 1018 Misses 119 119 ``` Help us with your feedback. Take ten seconds to tell us [how you rate us](https://about.codecov.io/nps?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=aiidateam). Have a feature suggestion? [Share it here.](https://app.codecov.io/gh/feedback/?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=aiidateam)

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