remove 3.9 as it is no longer supported

Author: KennethEnevoldsen

.github/workflows/tests.yml

@@ -11,7 +11,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest, macos-latest, windows-latest]
-        python-version: ["3.9", "3.10", "3.11"]
+        python-version: ["3.10", "3.11"]
 
     # This allows a subsequently queued workflow run to interrupt previous runs
     concurrency: