Rebuild on target branch change

Right now we have some logic in our pipeline’s generation script (note I think the same applies with buildkite conditionals as well) that runs different sets of jobs depending on what branch the build is targeting, today if a user changes the target branch of their pull request on github, CI doesn’t re-run, which potentially means missing some of these jobs.

It would be great if we could setup that webhook and have it rerun the jobs when it changes.

Thanks @Keith! I have passed this onto our product team for their consideration!