Add Python v3.15 support and drop Python v3.10
### Python 3.15 pre-releases
- [ ] Set up v3.15 test job
- [ ] With `allow_failure: true`, to allow tests to fail
### Python 3.15 stable release
- [ ] Handle deprecation warning and breaking features
- [ ] Remove `allow_failure: true`, now on the tests should pass
### Drop Python 3.10 support
- [ ] Delete test job for v3.10 from `.gitlab-ci.yml`
- [ ] `pyproject.toml`: Bump minimum versions:
- [ ] `tools.poetry.dependency.python`
- [ ] remove `tools.ruff.target-version`
### Post
- [ ] Open follow-up v3.11/3.16 ticket
### References
- Expected to be release the [October 1st 2026](https://devguide.python.org/versions/)?
- docker/python3/poetry#13+
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