perf: remove unnecessary Python matrix strategy

- Use Python 3.11 only (no version-specific code in notebooks)
- Reduces CI runtime by 50%
- Reduces API costs by 50% for notebook execution
- Simplifies PR checks (one instead of two identical)

Author: zealoushacker

.github/workflows/notebook-quality.yml

@@ -18,9 +18,6 @@ permissions:
 jobs:
   validate-notebooks:
     runs-on: ubuntu-latest
-    strategy:
-      matrix:
-        python-version: ['3.11', '3.12']
 
     steps:
       - uses: actions/checkout@v4
@@ -31,8 +28,8 @@ jobs:
           enable-cache: true
           cache-dependency-glob: "uv.lock"
 
-      - name: Set up Python ${{ matrix.python-version }}
-        run: uv python install ${{ matrix.python-version }}
+      - name: Set up Python 3.11
+        run: uv python install 3.11
 
       - name: Install dependencies
         run: |
@@ -92,6 +89,6 @@ jobs:
         if: always()
         uses: actions/upload-artifact@v4
         with:
-          name: notebook-test-outputs-py${{ matrix.python-version }}
+          name: notebook-test-outputs
           path: test_outputs/
           retention-days: 7