Bump coverage from 5.3.1 to 5.4 (GeoNode#6903)

Bumps [coverage](https://github.com/nedbat/coveragepy) from 5.3.1 to 5.4.
- [Release notes](https://github.com/nedbat/coveragepy/releases)
- [Changelog](https://github.com/nedbat/coveragepy/blob/master/CHANGES.rst)
- [Commits](nedbat/coveragepy@coverage-5.3.1...coverage-5.4)

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

requirements.txt

@@ -143,7 +143,7 @@ docker==4.4.1
 invoke==1.5.0
 
 # tests
-coverage==5.3.1
+coverage==5.4
 parse-type==0.5.2
 requests-toolbelt==0.9.1
 flake8==3.8.4