Make rubydoc.brew.sh workflow more like formulae.brew.sh

[MikeMcQuaid]

Verification

• This issue's title and/or description do not reference a single formula e.g. brew install wget. If they do, open an issue at https://github.com/Homebrew/homebrew-core/issues/new/choose instead.

Provide a detailed description of the proposed feature

Homebrew/rubydoc.brew.sh has a "Scheduled regeneration" GitHub Action which commits changes to the repository and pushes them. This is a bit like what Homebrew/formulae.brew.sh used to do, too.

Instead, it should make use of the GitHub Pages v4 deployment mechanism which doesn't require generated files to be committed.

This can also mean that PRs are required on this repository.

What is the motivation for the feature?

Enabling additional security features on Homebrew/rubydoc.brew.sh.

How will the feature be relevant to at least 90% of Homebrew users?

It won't be.

What alternatives to the feature have been considered?

(note: opening on Homebrew/brew for improved visibility)

[MikeMcQuaid]

This was done, thanks @Rylan12!