ci: Add Python 3.10, 3.11 and drop 3.6

Python 3.6 is dropped because setup-python no longer supports it.

Author: kadler

.github/workflows/build.yml

@@ -16,10 +16,11 @@ jobs:
       fail-fast: false
       matrix:
         python-version:
+        - '3.11'
+        - '3.10'
         - '3.9'
         - '3.8'
         - '3.7'
-        - '3.6'
 
     steps:
     - uses: actions/checkout@v1