Bump codecov/codecov-action from 2 to 3 (#45)

Bumps [codecov/codecov-action](https://github.com/codecov/codecov-action) from 2 to 3.
- [Release notes](https://github.com/codecov/codecov-action/releases)
- [Changelog](https://github.com/codecov/codecov-action/blob/main/CHANGELOG.md)
- [Commits](codecov/codecov-action@v2...v3)

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

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

.github/workflows/format_test.yml

@@ -54,7 +54,7 @@ jobs:
         dart run coverage:format_coverage --lcov --in=coverage \
           --out=coverage/lcov.info --report-on=lib
     - name: Upload coverage to Codecov
-      uses: codecov/codecov-action@v2
+      uses: codecov/codecov-action@v3
       with:
         token: ${{ secrets.CODECOV_TOKEN }}
         verbose: true