fix(ci): remove Python 3.9 from unittest matrix

This removes Python 3.9 from the unittest matrix in unittest.yml.

Author: chalmerlowe

.github/workflows/unittest.yml

@@ -17,7 +17,7 @@ jobs:
     runs-on: ubuntu-22.04
     strategy:
       matrix:
-        python: ['3.9', '3.10', "3.11", "3.12", "3.13", "3.14"]
+        python: ['3.10', "3.11", "3.12", "3.13", "3.14"]
     steps:
     - name: Checkout
       uses: actions/checkout@v4