chore: pin python-version for Lint and Test Charts workflow (#18)

Author: MykhailoRyzhman

.github/workflows/lint-test.yaml

@@ -21,7 +21,7 @@ jobs:
       - name: Set up Python
         uses: actions/setup-python@e797f83bcb11b83ae66e0230d6156d7c80228e7c # v6.0.0
         with:
-          python-version: 3.x
+          python-version: 3.13.7
 
       - name: Set up chart-testing
         uses: helm/chart-testing-action@0d28d3144d3a25ea2cc349d6e59901c4ff469b3b # v2.7.0