Remove deprecated czConfig

[jimthedev]

#30 added deprecation warnings and switched defaults over to using config.commitizen in package.json. We just need to remove the deprecated code for 3.0.0 but this'll be a breaking change.

[jimthedev]

Closed by 3a3d10d, right @LinusU?

[LinusU]

Yes, I didn't know it I should close it now or when we merge v3.x into master :) up to you 👌