Fix Dependabot vulnerable deps by dropping EOL Python 3.9 (#823)

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

.github/workflows/test_and_build.yaml

@@ -41,7 +41,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python-version: ['3.9', '3.12', '3.13']
+        python-version: ['3.10', '3.12', '3.13']
     steps:
     - name: Checkout code
       uses: actions/checkout@v4