ci: install python3.8 for code ql

.github/workflows/codeql-analysis.yml

@@ -26,7 +26,9 @@ jobs:
     # the head of the pull request instead of the merge commit.
     - run: git checkout HEAD^2
       if: ${{ github.event_name == 'pull_request' }}
-
+    - uses: actions/setup-python@v2
+      with:
+        python-version: '3.8'
     # Initializes the CodeQL tools for scanning.
     - name: Initialize CodeQL
       uses: github/codeql-action/init@v1