Add Python 3.11.

Author: aaugustin

.github/workflows/tests.yml

@@ -43,6 +43,7 @@ jobs:
           - "3.8"
           - "3.9"
           - "3.10"
+          - "3.11"
           - "pypy-3.7"
           - "pypy-3.8"
           - "pypy-3.9"