Fix GitHub action with PyPy 3.9

Author: Cito

.github/workflows/test-package.yml

@@ -10,7 +10,7 @@ jobs:
     strategy:
       max-parallel: 4
       matrix:
-        python-version: ['3.7', '3.8', '3.9', '3.10', '3.11', 'pypy3.9']
+        python-version: ['3.7', '3.8', '3.9', '3.10', '3.11', 'pypy-3.9']
 
     steps:
     - uses: actions/checkout@v3