Skip cog check on Python 3.6, refs #501

Author: simonw

.github/workflows/test.yml

@@ -49,5 +49,6 @@ jobs:
     - name: Check formatting
       run: black . --check
     - name: Check if cog needs to be run
+      if: matrix.python-version != '3.6'
       run: |
         cog --check README.md docs/*.rst