Drop Windows/3.9 build due to unrelated failures

Author: joshmoore

.github/workflows/windows-testing.yml

@@ -16,7 +16,7 @@ jobs:
     strategy:
       fail-fast: True
       matrix:
-        python-version: ['3.9', '3.10', '3.11']
+        python-version: ['3.10', '3.11']
     steps:
       - uses: actions/checkout@v4
         with: