build: add pypy 3.8 & 3.9 to github actions

Author: mbdevpl

.github/workflows/python.yml

@@ -12,7 +12,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest, macos-latest, windows-latest]
-        python-version: ['3.8', '3.9', '3.10', '3.11']
+        python-version: ['3.8', 'pypy3.8', '3.9', 'pypy3.9', '3.10', '3.11']
 
     steps:
       - uses: actions/checkout@v3