Remove Python 3.8 from CI workflow

Author: ndem0

.github/workflows/testing_pr.yml

@@ -12,7 +12,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [windows-latest, macos-latest, ubuntu-latest]
-        python-version: ["3.8", "3.9", "3.10", "3.11", "3.12"]        
+        python-version: ["3.9", "3.10", "3.11", "3.12"]        
     steps:
     - uses: actions/checkout@v2