Removed testing for python 3.9 since networkx 3.4 requires >=3.10

Author: jmafoster1

.github/workflows/ci-tests.yaml

@@ -18,7 +18,7 @@ jobs:
     strategy:
       matrix:
         os: ["ubuntu-latest", "windows-latest", "macos-latest"]
-        python-version: ["3.9", "3.10", "3.11", "3.12"]
+        python-version: ["3.10", "3.11", "3.12"]
     steps:
     - uses: actions/checkout@v4
     - name: Set up Python