Bump codecov/codecov-action from 1 to 2

Bumps [codecov/codecov-action](https://github.com/codecov/codecov-action) from 1 to 2.
- [Release notes](https://github.com/codecov/codecov-action/releases)
- [Changelog](https://github.com/codecov/codecov-action/blob/master/CHANGELOG.md)
- [Commits](codecov/codecov-action@v1...v2.0.1)

---
updated-dependencies:
- dependency-name: codecov/codecov-action
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

.github/workflows/tests.yml

@@ -230,7 +230,7 @@ jobs:
           find . -name '*.gc*' -delete
         if: ${{ runner.os != 'macOS' }}
       - name: Upload code coverage
-        uses: codecov/codecov-action@v1
+        uses: codecov/codecov-action@v2
 
       - uses: actions/upload-artifact@v2
         if: failure()