GitHub workflow _test.yml: Temporarily reduced Python versions to only 3.11

Author: ClaasRostock

.github/workflows/_test.yml

@@ -10,7 +10,7 @@ jobs:
       fail-fast: true
       matrix:
         os: [ubuntu-latest, windows-latest]
-        python: ['3.11', '3.12', '3.13', '3.14']
+        python: ['3.11'] # , '3.12', '3.13', '3.14']
     steps:
       - name: Checkout code
         uses: actions/checkout@v5