Update automated Pull Request step in GH Action to use a GitHub App instead of PAT token

[sdolgin]

The existing step in the translate action needs to be updated to use a custom GitHub app which doesn't rely on PAT for it's permissions.

See the following blog for more info on this approach...
https://josh-ops.com/posts/github-apps/

[erjosito]

I am reading there that "You’ll have to be an organization owner to create an app that’s owned by the organization, and only organization owners can install a GitHub App"... I will try to ask for the app creation, let's see what comes back.