build(deps): bump pylint from 2.5.3 to 2.6.0

Bumps [pylint](https://github.com/PyCQA/pylint) from 2.5.3 to 2.6.0.
- [Release notes](https://github.com/PyCQA/pylint/releases)
- [Changelog](https://github.com/PyCQA/pylint/blob/master/ChangeLog)
- [Commits](pylint-dev/pylint@pylint-2.5.3...pylint-2.6.0)

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

Author: dependabot[bot]

travis/requirements.txt

@@ -1,6 +1,6 @@
 coverage==5.2.1
 freezegun==0.3.15
-pylint==2.5.3
+pylint==2.6.0
 pytest==5.4.3
 pytest-asyncio==0.14.0
 pytest-cov==2.10.1