Schema generator PR doesn't stay up to date with master

[robere2]

The schema generator's base branch does not automatically stay up to date with master. This is so we can stack multiple generator outputs into one PR (i.e. if the generator PR isn't merged for a week, if we want all of the generations to be included in the PR, we need to base each generation on the previous one). On the flip side, this means if master gets ahead, we need to somehow get our PR up to date.

I think if the action should check if we can gracefully rebase schemas/patch onto master, and do it if so. If not, reset schemas/patch back to master, thereby discarding changes, before running the generator again.

For now, we can manually rebase the branch, or close the PR and delete the branch to discard changes.