Automatically update OpenAPI descriptions and generated code

[WillAbides]

IMPORTANT This requires that this repo's permissions allows GitHub Actions to create PRs. See instructions.

This adds a GitHub Actions Workflow to create a PR when go-github's generated files are out of date with https://github.com/github/rest-api-description.

It runs daily at 15:23 UTC -- an arbitrarily picked time.

Here is an example PR from my fork: WillAbides#15

[gmlewis]

Thank you, @WillAbides !

I am no longer authorized to modify this repo's settings, but @willnorris may still be authorized. If not, he would know who is.

But at the very least, I would like @willnorris to approve this PR and make sure he is OK with it running nightly to ensure that all the metadata is up-to-date, so I am going to add him as a reviewer. He can loop in any other approvers needed from the Google OSPO team if needed.

[willnorris]

The change seems reasonable, and I don't have any strong opinions about it. I wasn't even aware we were using the OpenAPI spec for anything... interesting.

One thing I've done on other repos that automatically open pull requests is to authenticate with a GitHub App rather than a personal access token, so that it's not tied to any single user. You can see an example here that uses https://github.com/tibdex/github-app-token to get the token.

But that also requires additional work to create the app, get the credentials, etc. Which comes to the final point... I don't have admin access to this repo either. I can reach out to the Google OSPO contacts I do have and see if they've got anyone that can step in and help.