Pin GitHub Actions to Python 3.13 to match local virtualenv

- Remove matrix testing against Python 3.10, 3.11, 3.12
- Use Python 3.13 exclusively in both test and lint jobs
- Matches local development environment (Python 3.13.7)
- Ensures consistent behavior between local and CI environments

.github/workflows/test.yml

@@ -14,18 +14,15 @@ concurrency:
 jobs:
   test:
     runs-on: ubuntu-latest
-    strategy:
-      matrix:
-        python-version: ['3.10', '3.11', '3.12']
 
     steps:
     - name: Checkout code
       uses: actions/checkout@v4
 
-    - name: Set up Python ${{ matrix.python-version }}
+    - name: Set up Python 3.13
       uses: actions/setup-python@v5
       with:
-        python-version: ${{ matrix.python-version }}
+        python-version: '3.13'
         cache: 'pip'
 
     - name: Install dependencies
@@ -67,10 +64,10 @@ jobs:
     - name: Checkout code
       uses: actions/checkout@v4
 
-    - name: Set up Python
+    - name: Set up Python 3.13
       uses: actions/setup-python@v5
       with:
-        python-version: '3.11'
+        python-version: '3.13'
         cache: 'pip'
 
     - name: Install linting dependencies