Add Python 3.9 to CI workflow

Author: surister

.github/workflows/tests.yml

@@ -19,7 +19,7 @@ jobs:
       fail-fast: false
       matrix:
         os: ['ubuntu-22.04']
-        python-version: ['3.10', '3.11', '3.12', '3.13', '3.14']
+        python-version: ['3.9', '3.10', '3.11', '3.12', '3.13', '3.14']
         cratedb-version: ['nightly']
 
         # To save resources, only verify the most recent Python versions on macOS.