ci: pin actions/setup-python to v7 in star_history workflow (#11191)

The star_history workflow referenced actions/setup-python@v8, which
does not exist, causing the workflow to fail at the "Set up job" step.
Pin to v7, matching the version used across the other workflows.

.github/workflows/star_history.yml

@@ -19,7 +19,7 @@ jobs:
         uses: actions/checkout@v7
 
       - name: Set up Python
-        uses: actions/setup-python@v8
+        uses: actions/setup-python@v7
         with:
           python-version: "3.x"
           cache: pip