Bump codecov/codecov-action from 1.5.2 to 2.0.1 (#351)

Author: dependabot[bot]

.github/workflows/tests.yaml

@@ -98,4 +98,4 @@ jobs:
           poetry run coverage combine coverage*/.coverage*
           poetry run coverage xml -i
       - name: 🚀 Upload coverage report
-        uses: codecov/codecov-action@v1.5.2
+        uses: codecov/codecov-action@v2.0.1