Remove python 3.10 from testing matrix.

It was taking forever to build on GitHub actions.

Author: SamEdwardes

.github/workflows/pytest.yml

@@ -16,7 +16,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python-version: ["3.6", "3.7", "3.8", "3.9", "3.10"]
+        python-version: ["3.6", "3.7", "3.8", "3.9"]
 
     steps:
     - uses: actions/checkout@v2