Only use Python 3.7 for Python tests

Author: adbridge

.github/workflows/basic_checks.yml

@@ -142,7 +142,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python-version: [ '3.5', '3.6', '3.7' ]
+        python-version: [ '3.7' ]
 
     steps:
       -