Add allow-prereleases to windows CI to try and run 3.15

Author: seberg

.github/workflows/test-wheel-windows.yml

@@ -277,6 +277,8 @@ jobs:
         uses: actions/setup-python@ece7cb06caefa5fff74198d8649806c4678c61a1  # v6.3.0
         with:
           python-version: ${{ matrix.PY_VER }}
+          # TODO: remove allow-prereleases once 3.15 is officially supported
+          allow-prereleases: ${{ startsWith(matrix.PY_VER, '3.15') }}
 
       - name: Enable Scientific Python Nightly Wheels for Python 3.15
         if: ${{ startsWith(matrix.PY_VER, '3.15') }}