Add Python 3.11 to test matrix (#666)

Author: Secrus

.github/workflows/tests.yml

@@ -19,7 +19,7 @@ jobs:
     strategy:
       matrix:
         os: [Ubuntu, MacOS, Windows]
-        python-version: [3.7, 3.8, 3.9, "3.10"]
+        python-version: [3.7, 3.8, 3.9, "3.10", "3.11"]
     defaults:
       run:
         shell: bash