feat: add ability to specify triggering files

[avegancafe]

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

This is a super useful package. In my specific use-case I'm working in a pretty large monolith where there are a significant number of people that only work in ruby, so a significant portion of the PRs opened in the repo don't change any js.

Describe the solution you'd like

It would be cool if we could specify a list of files that would cause this action to only execute and comment and such if those specified files were changed.

Describe alternatives you've considered

Not sure if there is an alternative besides ignoring the comment a majority of the time. It is pretty slow though currently since there's no caching, so might also end up being added noise for a significant percentage of PRs.