CI: Ensure GHA uses major versions of actions
* Change `@master` to `@<major version>` for more stability
* Change specifically pinned version to `@<major version>` to ensure bug & security changes are picked up
* Bump actions/github-script from `@v4` to `@v5`

@mroeschke ok to backport? @meeseeksdev backport 1.4.x > @mroeschke ok to backport?

Yes should be good. Thank you.

https://github.com/pandas-dev/pandas/pull/45391 was also a followup to this but it only impacts the current repository state so will leave that up to you