ci: remove python 3.9 from unit tests matrix (#126)

Author: DeanChensj

.github/workflows/unit-tests.yaml

@@ -12,7 +12,7 @@ jobs:
     strategy:
       matrix:
         # Test against all Python versions supported in pyproject.toml
-        python-version: ["3.9", "3.10", "3.11", "3.12", "3.13"]
+        python-version: ["3.10", "3.11", "3.12", "3.13"]
 
     steps:
       - name: Checkout code