Fix Python 3.6 CI checks

Author: Martchus

.github/workflows/tox.yml

@@ -21,7 +21,7 @@ jobs:
         include:
           - os: "ubuntu-latest"
           - os: "ubuntu-20.04"
-            python-version: "3.6"
+            python-version: "3.11"
 
     steps:
       - uses: actions/checkout@v4