chore(deps-dev): bump coverage from 7.2.7 to 7.3.1 in /requirements (#541)

* chore(deps-dev): bump coverage from 7.2.7 to 7.3.1 in /requirements

Bumps [coverage](https://github.com/nedbat/coveragepy) from 7.2.7 to 7.3.1.
- [Release notes](https://github.com/nedbat/coveragepy/releases)
- [Changelog](https://github.com/nedbat/coveragepy/blob/master/CHANGES.rst)
- [Commits](nedbat/coveragepy@7.2.7...7.3.1)

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

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

* fix: set coverage versions based on python versions

- since coverage 7.3.x python3.7 support has been dropped.

---------

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

Author: dependabot[bot]

requirements/dev.txt

@@ -1,4 +1,5 @@
-coverage==7.2.7
+coverage==7.2.7; python_version < '3.8'
+coverage==7.3.1; python_version >= '3.8'
 flake8==3.3.0; python_version < '3.8'
 flake8==3.8.4; python_version >= '3.8'
 pytest-cov==4.1.0