Update pytest-cov requirement from ~=2.12 to ~=3.0
Updates the requirements on [pytest-cov](https://github.com/pytest-dev/pytest-cov) to permit the latest version.
- [Release notes](https://github.com/pytest-dev/pytest-cov/releases)
- [Changelog](https://github.com/pytest-dev/pytest-cov/blob/master/CHANGELOG.rst)
- [Commits](https://github.com/pytest-dev/pytest-cov/compare/v2.12.0...v3.0.0)
---
updated-dependencies:
- dependency-name: pytest-cov
dependency-type: direct:production
...
Signed-off-by: dependabot[bot] <support@github.com>