dependabot seems to submit PRs without running 'make vendor'.
This script automates (with some safety checks) the manual
process for pulling the PR, running 'make vendor-in-container',
and force-pushing the PR.
Usage: ./contrib/dependabot-dance
It should take care of identifying your github repo, finding
all active dependabot branches, running the make, git-add,
and commit, then git-pushing.
Signed-off-by: Ed Santiago <santiago@redhat.com>