Use FORCE_COLOR instead of CLI args (#839)

Author: bhrutledge

.github/workflows/main.yml

@@ -6,6 +6,10 @@ on:
   schedule:
     - cron: "0 0 * * *" # daily
 
+env:
+  FORCE_COLOR: "1"
+  TOX_TESTENV_PASSENV: "FORCE_COLOR"
+
 jobs:
   lint:
     runs-on: ubuntu-latest
@@ -43,7 +47,7 @@ jobs:
       - name: Run type-checking
         run: python -m tox -e types
       - name: Run tests
-        run: python -m tox -e py -- --cov-report xml --color yes
+        run: python -m tox -e py -- --cov-report xml
       - uses: codecov/codecov-action@v1
         if: github.event_name != 'schedule'
         with: