Add support for completion on zsh with homebrew installation

[remyleone]

Is your feature request related to a problem? Please describe.

I would like to have ZSH shell completion for options of gitlab-ci-local

Describe the solution you'd like

when I do a brew install gitlab-ci-local I get gitlab-ci-local installed with completion file installed in default shell completion folder.

Describe alternatives you've considered

Install it manually, the problem is that I would have to do it everytime for each new version.

[firecow]

Can you please explain, why you have to do it everytime a new version is installed @remyleone

[remyleone]

Maybe the completion mechanisms within gitlab-ci-local would change from one version to the next, having it installed automatically when the formula is installed ensure that the completion feature will stay up to date

[firecow]

I'm pretty sure it won't change.

But yeah sure, if its possible to build into the homebrew process somehow.