Drop python3.6 and add python3.10 unit tests (#69)

Co-authored-by: Daniel McKnight <[email protected]>

.github/workflows/unit_tests.yml

@@ -9,7 +9,7 @@ jobs:
   unit_tests:
     strategy:
       matrix:
-        python-version: [3.6, 3.7, 3.8, 3.9]
+        python-version: [3.7, 3.8, 3.9, '3.10']
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v2