[lesnik512]

Summary

CPython 3.15.0 is out. This adds 3.15 and 3.15t to the pytest matrix and the floors matrix and the 3.15 classifier.

Changes

• _checks.yml: add 3.15 and 3.15t to pytest and floors. Every check keyed on 3.14t now matches any t build.
• pyproject.toml: add the Programming Language :: Python :: 3.15 classifier.

Checklist

• Every job with a 3.15 entry passes locally on 3.15.0 and 3.15.0t, run step by step from this _checks.yml