CI: Drop max-parallel limitation

Author: effigies

.github/workflows/test.yml

@@ -20,7 +20,6 @@ jobs:
 
     runs-on: ubuntu-latest
     strategy:
-      max-parallel: 4
       matrix:
         python-version: ['3.8', '3.9', '3.10', '3.11', '3.12']
         requires: ['requirements.txt']