ci: test Python 3.15 and 3.15t as supported versions (#48)

Author: lesnik512

.github/workflows/_checks.yml

@@ -77,7 +77,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python-version: ["3.11", "3.12", "3.13", "3.14", "3.14t"]
+        python-version: ["3.11", "3.12", "3.13", "3.14", "3.14t", "3.15", "3.15t"]
     steps:
       - uses: actions/checkout@v6
       - uses: extractions/setup-just@v4
@@ -89,6 +89,6 @@ jobs:
       - run: uv python pin ${{ matrix.python-version }}
       - run: just install
       - name: Confirm the interpreter is free-threaded
-        if: matrix.python-version == '3.14t'
+        if: endsWith(matrix.python-version, 't')
         run: uv run --no-sync python -c "import sys, release_scope; assert not sys._is_gil_enabled(), 'GIL is enabled on a t-build'"
       - run: just test-ci

pyproject.toml

@@ -13,6 +13,7 @@ classifiers = [
     "Programming Language :: Python :: 3.12",
     "Programming Language :: Python :: 3.13",
     "Programming Language :: Python :: 3.14",
+    "Programming Language :: Python :: 3.15",
     "Programming Language :: Python :: Free Threading :: 2 - Beta",
     "Typing :: Typed",
     "Topic :: Software Development :: Build Tools",