Update vcr requirement to ~> 4
Update vcr requirement to ~> 4

Updates the requirements on [vcr](https://github.com/vcr/vcr) to permit the latest version.
- [Changelog](https://github.com/vcr/vcr/blob/master/CHANGELOG.md)
- [Commits](https://github.com/vcr/vcr/commits/v4.0.0)
JoeSouthan/citywrapper,JoeSouthan/citywrapper