Bump codecov from 2.0.15 to 2.1.13

Bumps [codecov](https://github.com/codecov/codecov-python) from 2.0.15 to 2.1.13.
- [Release notes](https://github.com/codecov/codecov-python/releases)
- [Changelog](https://github.com/codecov/codecov-python/blob/master/CHANGELOG.md)
- [Commits](codecov/codecov-python@v2.0.15...v2.1.13)

---
updated-dependencies:
- dependency-name: codecov
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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