Add Homebrew package manager automatic deployment

[Gmossak]

I've added the pgcopydb formula to Homebrew to ease installation for macOS and Linux https://github.com/Homebrew/homebrew-core/pull/181675. Simply run

brew install pgcopydb

To keep it updated a new and simple workflow should be created to update (or bump) the Homebrew format upon the pgcopydb release.

It's straightforward, you only need to run the brew bump-formula-pr CLI command in order to open PR which would upgrade the formula. Or even easier you can use the following GitHub Action https://github.com/mislav/bump-homebrew-formula-action

I would do it myself but it requires a GitHub Action secret to be added.

After that, we can add Homebrew as a supported installation method.