Drop Python 3.10 and add Python 3.15 support

[tefra]

Python 3.10 reaches end of life in October 2026, and 3.15 is out the same month. This moves the supported range to 3.11–3.15.

Changes

• Require Python >=3.11. Drop the 3.10 classifier and add 3.15.
• CI: drop 3.10 from the test matrix and add 3.15. The w3c and samples jobs that were pinned to 3.10 now run on 3.11.
• Remove the _eval_type backport in xsdata/formats/dataclass/typing.py. Only 3.9 and 3.10 needed it (bpo-41370: Evaluate strings as forward refs in PEP 585 generics python/cpython#30900).
• Set ruff target-version to py311, both for the codebase and in xsdata/formats/dataclass/ruff.toml, which formats generated code.
• Switch datetime.timezone.utc to datetime.UTC, which ruff UP017 flags under the new target.
• Docs now say Python 3.11+.
• Drop the typing-extensions dependency. Nothing in xsdata or the generated code imports it. Code that imports typing_extensions but only got it installed through xsdata now needs to depend on it directly.
• Track mise.toml, pinned to Python 3.11, the oldest supported version. mise now creates the venv with uv, and the install task uses uv pip.

Testing

• pytest passes on 3.11 and 3.14. 3.15 is covered by the new CI job only.
• mypy and ruff pass.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.97%. Comparing base (4fae5cc) to head (ec097cf).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1241      +/-   ##
==========================================
- Coverage   99.97%   99.97%   -0.01%     
==========================================
  Files         117      117              
  Lines        9421     9412       -9     
  Branches     1448     1446       -2     
==========================================
- Hits         9419     9410       -9     
  Misses          1        1              
  Partials        1        1              

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud