Bump pytest-pylint from 0.18.0 to 0.21.0

Bumps [pytest-pylint](https://github.com/carsongee/pytest-pylint) from 0.18.0 to 0.21.0.
- [Release notes](https://github.com/carsongee/pytest-pylint/releases)
- [Commits](carsongee/pytest-pylint@v0.18.0...v0.21.0)

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

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

requirements/requirements_dev.txt

@@ -15,4 +15,4 @@ pytest-black==0.3.12
 pytest-cov==4.0.0
 pytest-datadir==1.4.1
 pytest-mock==3.10.0
-pytest-pylint==0.18.0
+pytest-pylint==0.21.0