Bump coverage from 5.4.0 to 5.5

Bumps [coverage](https://github.com/nedbat/coveragepy) from 5.4.0 to 5.5.
- [Release notes](https://github.com/nedbat/coveragepy/releases)
- [Changelog](https://github.com/nedbat/coveragepy/blob/master/CHANGES.rst)
- [Commits](coveragepy/coveragepy@coverage-5.4...coverage-5.5)

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

Author: dependabot[bot]

requirements_test.txt

@@ -1,7 +1,7 @@
 -r requirements_test_pre_commit.txt
 -r requirements_test_min.txt
 coveralls==3.0.0
-coverage==5.4.0
+coverage==5.5
 pre-commit==2.10.1
 pyenchant==3.2.0
 pytest-cov==2.11.1