Adding package requires using main branch

[justin]

I don't know if I would necessarily call it a bug since it's your project and you're actively working on it, but it might be worth updating the README to point out that you need to pin the package to the main branch instead of a tag because FZSwiftUtils, FZUIKit, and FZQuicklook are pinned to their main respective branches (I think this is the reason?)

Just FYI!