Update pre-commit requirement from ~=1.21 to ~=2.1 (#506)

Updates the requirements on [pre-commit](https://github.com/pre-commit/pre-commit) to permit the latest version.
- [Release notes](https://github.com/pre-commit/pre-commit/releases)
- [Changelog](https://github.com/pre-commit/pre-commit/blob/master/CHANGELOG.md)
- [Commits](pre-commit/pre-commit@v1.21.0...v2.1.0)

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

Author: dependabot-preview[bot]

Pipfile

@@ -4,7 +4,7 @@ url = "https://pypi.org/simple"
 verify_ssl = true
 
 [dev-packages]
-pre-commit = "~=1.21"
+pre-commit = "~=2.1"
 
 [packages]
 selenium = "~=3.141"