refactor: remove unused ansicolor dependency

[Benjaminpjacobs]

The term-ansicolor gem injects a global Term module that has a high probability of naming collision for other common class names. This PR removes that gem from this repo as it is not used anywhere.

[bethesque]

I don't think this is necessary - it will auto update anyway with a bundle update.

[Benjaminpjacobs]

@bethesque this whole PR is unnecessary? My only concern is that if the gem is included, even if it's not referenced, it might still pollute the namespace.

[YOU54F]

I think we can remove gem.add_runtime_dependency 'term-ansicolor', '~> 1.0' as its not used like you point out, but we don't need to update the pact-mock-service to fix to the patch version, the minor version will mean it will pick up the latest, 1.19.

I've included this in #141 Thanks!