renovate PRs automatically rebase and kick off CI every time `master` is updated

[brian-smith-tcril]

As of writing, there are 10 open renovate PRs.

When anything is merged to master, the renovate bot rebases the PRs which triggers the CI.

This is problematic for a few reasons:

• With 10 open renovate PRs, a large number of jobs are kicked off simultaneously every time something is merged to master.
• Renovate PRs that are open for a long time are responsible for a ton of CI runs
  • For example: the webpack renovate PR has been rebased 37 times since it was opened.

This would not be an issue if renovate PRs were merged in a timely fashion.