Mock git to increase test coverage

[stevemao]

conventional-changelog/standard-version#33 😄

[stevemao]

Use https://github.com/stevemao/mock-git

[fpereira1]

@stevemao would this be ok for a first-timer? I looked into the other open issue labeled help wanted, but this issue seems like it would most benefit the project. Thanks

[stevemao]

@fpereira1 Feel free to send a PR :)

[hutson]

We're closing this issue out as this repository has been merged into our conventional-changelog mono-repository.

If you would like to see this change incorporated into conventional-changelog please consider re-opening the issue against the conventional-changelog mono-repository.