Test with Python 3.11-dev

Author: hugovk

.github/workflows/pythonapp.yml

@@ -38,7 +38,7 @@ jobs:
     strategy:
       matrix:
         # todo: extract from source
-        python-version: [2.7, 3.5, 3.6, 3.7, 3.8, 3.9, "3.10"]
+        python-version: [2.7, 3.5, 3.6, 3.7, 3.8, 3.9, "3.10", "3.11-dev"]
         install-from: ["dist/*.whl"]
         include:
         - python-version: "3.10"