Bump pylint from 2.7.2 to 2.7.4

Bumps [pylint](https://github.com/PyCQA/pylint) from 2.7.2 to 2.7.4.
- [Release notes](https://github.com/PyCQA/pylint/releases)
- [Changelog](https://github.com/PyCQA/pylint/blob/master/ChangeLog)
- [Commits](https://github.com/PyCQA/pylint/compare/pylint-2.7.2...pylint-2.7.4)

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

requirements-dev.txt

@@ -2,7 +2,7 @@ mock==4.0.3
 nose2[coverage_plugin]==0.10.0
 cov-core==1.15.0
 pycodestyle==2.6.0
-pylint==2.7.2
+pylint==2.7.4
 splinter==0.14.0
 transifex-client==0.14.2
 selenium==3.141.0