fix: ensure Python versions are strings in matrix

Ensure Python versions in the matrix are strings for consistency

Author: nishad

.github/workflows/python-tests.yaml

@@ -12,7 +12,7 @@ jobs:
     runs-on: ubuntu-22.04
     strategy:
       matrix:
-        python-version: [3.9, 3.10, 3.11, 3.12, 3.13]
+        python-version: ["3.9", "3.10", "3.11", "3.12", "3.13"]
 
     steps:
       - uses: actions/checkout@v4