chore(deps): update pylint requirement from ~=2.6 to ~=2.7 (appium#588)

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-2.6.0...pylint-2.7.0)

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Mori Atsushi <ki4070ma@gmail.com>

Author: dependabot[bot]

Pipfile

@@ -20,7 +20,7 @@ httpretty = "~=1.0"
 python-dateutil = "~=2.8"
 mock = "~=4.0"
 
-pylint = "~=2.6"
+pylint = "~=2.7"
 astroid = "~=2.5"
 isort = "~=5.7"