Fix GitHub Actions workflow: Update Python version requirements

- Update CI workflow to Python 3.9-3.12 (from 3.7-3.11)
- Python 3.7 and 3.8 no longer available on ubuntu-latest (Ubuntu 24.04)
- Add fail-fast: false to continue testing on failures
- Update all documentation to reflect Python 3.9+ requirement

Files updated:
- .github/workflows/tests.yml - New Python versions
- README.md - Badge updated to Python 3.9+
- CLAUDE.md - Prerequisites updated
- CONTRIBUTING.md - Prerequisites updated
- docs/MCP_SETUP.md - Prerequisites updated

This fixes the failing GitHub Actions tests.

.github/workflows/tests.yml

@@ -10,15 +10,16 @@ jobs:
   test:
     runs-on: ${{ matrix.os }}
     strategy:
+      fail-fast: false
       matrix:
         os: [ubuntu-latest, macos-latest]
-        python-version: ['3.7', '3.8', '3.9', '3.10', '3.11']
+        python-version: ['3.9', '3.10', '3.11', '3.12']
         exclude:
           # Exclude some combinations to speed up CI
           - os: macos-latest
-            python-version: '3.7'
+            python-version: '3.9'
           - os: macos-latest
-            python-version: '3.8'
+            python-version: '3.10'
 
     steps:
     - uses: actions/checkout@v3