chore(deps): update pylint requirement from ~=2.7 to ~=2.8 (#600)

Updates the requirements on [pylint](https://github.com/PyCQA/pylint) to permit the latest version.
- [Release notes](https://github.com/PyCQA/pylint/releases)
- [Changelog](https://github.com/PyCQA/pylint/blob/master/ChangeLog)
- [Commits](pylint-dev/pylint@pylint-2.7.0...pylint-2.8.1)

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

Author: dependabot[bot]

Pipfile

@@ -20,7 +20,7 @@ httpretty = "~=1.0"
 python-dateutil = "~=2.8"
 mock = "~=4.0"
 
-pylint = "~=2.7"
+pylint = "~=2.8"
 astroid = "~=2.5"
 isort = "~=5.8"