Test against python 3.10

Author: paul121

.github/workflows/run-tests.yml

@@ -17,7 +17,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python-version: [ 3.7, 3.8, 3.9 ]
+        python-version: [ 3.7, 3.8, 3.9, 3.10 ]
     steps:
       - name: Checkout the repository
         uses: actions/checkout@v2