feat: Enable "renovate changeset" action to work with dependabot

[ScottGuymer]

Add in the ability for the renovate changeset action to work with different dependency managers such as dependabot.

I needed/wanted to add this for our own plugins repo so thought it might be a worthwhile contribution.

I didnt go as far as renaming the action itself but that would make sense at some point (if this PR is accepted).

[freben]

Hi! What would we rename it to though? Would it make sense to make a second dedicated action for this instead, and move the commonalities as a helper into lib?

[ScottGuymer]

Maybe dependency-changeset or something like that.

maybe copy to a new action and then mark the current one as deprecated