Bump to newer codecov action (#996)

Author: sliverc

.github/workflows/tests.yml

@@ -29,7 +29,7 @@ jobs:
       - name: Test with tox
         run: tox
       - name: Upload coverage report
-        uses: codecov/codecov-action@v1
+        uses: codecov/codecov-action@v2
         with:
           env_vars: PYTHON,DJANGO,DJANGO_REST_FRAMEWORK
   check: