CI: (deps): Bump coverage from 7.3.0 to 7.3.1 in /ci

Bumps [coverage](https://github.com/nedbat/coveragepy) from 7.3.0 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@7.3.0...7.3.1)

---
updated-dependencies:
- dependency-name: coverage
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

ci/test_requirements.txt

@@ -2,5 +2,5 @@ packaging==23.1
 pytest==7.4.1
 pytest-mpl==0.16.1
 netCDF4==1.6.4
-coverage==7.3.0
+coverage==7.3.1
 dask==2023.9.0