Remove allow-prereleases option from Python setup

Not needed now Python 3.15 is out.

Author: simonw

.github/workflows/test.yml

@@ -19,7 +19,6 @@ jobs:
       uses: actions/setup-python@v7
       with:
         python-version: ${{ matrix.python-version }}
-        allow-prereleases: true
         cache: pip
         cache-dependency-path: pyproject.toml
         check-latest: true