Bump codecov from 2.0.15 to 2.0.16

Bumps [codecov](https://github.com/codecov/codecov-python) from 2.0.15 to 2.0.16.
- [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...v2.0.16)

---
updated-dependencies:
- dependency-name: codecov
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

requirements.txt

@@ -1,4 +1,4 @@
-codecov==2.0.15
+codecov==2.0.16
 mock==3.0.5
 pytest==4.5.0
 pytest-cov==2.7.1