Remove 3.9 from compatibility

Author: mvargas33

.github/workflows/main.yml

@@ -19,7 +19,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest]
-        python-version: ['3.6', '3.7', '3.8', '3.9']
+        python-version: ['3.6', '3.7', '3.8']
     steps:
       - uses: actions/checkout@v2
       - name: Set up Python