Support Python 3.12 and test in CI

[corneliusroemer]

Description of proposed changes

Requires bump of Biopython min tested version from 1.80 to 1.82 as it's the first to support 3.12.

In a future PR, we should also deprecate or even already remove Python 3.8 (has reached EOL October 31 and Biopython no longer supports it and has even already deprecated 3.9): https://github.com/nextstrain/augur/issues/1680

We can't support Python 3.13 yet because Biopython doesn't, see #1679

Related issue(s)

Closes #1536

Checklist

• [x] Automated checks pass
• [x] Check if you need to add a changelog message
• [x] Check if you need to add tests
• [x] Check if you need to update docs