[lesnik512]

Summary

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

The free-threaded smoke job gains a 3.15t entry with the same extras as 3.14t.

3.15 stays out of the floors matrix for now. Every target fails there: the orjson floor (3.11.1) predates the first 3.15 wheels (3.12.0), the fastapi and faststream targets pin pydantic floors whose pydantic-core predates the first 3.15 wheels (2.48.0), and the fastmcp and litestar targets pull PyYAML, which has no 3.15 wheels in any release. The floors job installs with --no-build, so it cannot pass on 3.15. Users on 3.15 get newer versions that install, and pytest covers those. Add 3.15 to floors once those are resolved.

Changes

• _checks.yml: add 3.15 to pytest. Add a 3.15t entry to free-threaded.
• pyproject.toml: add the Programming Language :: Python :: 3.15 classifier.
• README.md says lite-bootstrap runs on free-threaded 3.14t and 3.15t.
• tests/test_types.py: test repr(UNSET) directly. On 3.14 the only caller was dataclasses itself: it formats the class signature when FastAPIConfig is created, and that formats the UNSET default. 3.15 no longer does that at class creation, so UnsetType.__repr__ dropped out of coverage and the 3.15 pytest job failed the 100% gate.

Checklist

• The free-threaded smoke job passes locally on 3.15.0t
• The new test passes on 3.15.0 and covers lite_bootstrap/types.py fully; the full suite stays at 100% on 3.14
• The full pytest job on 3.15.0 runs only in CI: pyroscope-io has no 3.15 wheel and builds from source with Rust, which the machine I tested on lacks
• The floors install fails locally on 3.15 for the reason above