disable pre-releases for 3.15

Author: daniel-sanche

.github/workflows/unittest.yml

@@ -132,11 +132,6 @@ jobs:
     - name: Install nox and nox-uv
       run: |
         uv pip install --system nox nox-uv
-    # TODO(https://github.com/googleapis/google-cloud-python/issues/18532):
-    # Remove UV_PRERELEASE once Python 3.15 is officially released and upstream binary wheels are available.
-    - name: Enable prereleases for Python 3.15
-      if: matrix.python == '3.15'
-      run: echo "UV_PRERELEASE=allow" >> $GITHUB_ENV
     - name: Run unit tests for ${{ matrix.package_shard.description }}
       env:
         BUILD_TYPE: presubmit