Modify Python versions in tests workflow (#133)

Updated Python version from 'pypy-3.9' to 'pypy-3.11' in workflow.

Author: auvipy

.github/workflows/tests.yml

@@ -10,7 +10,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest, windows-latest]
-        python-version: ['3.8', '3.9', '3.10', '3.11', '3.12', 'pypy-3.9']
+        python-version: ['3.9', '3.10', '3.11', '3.12', 'pypy-3.11']
         click-version: ['7.1.2', '8.1.2']
 
     steps: