`commit.get_pulls()` in PyGithub returns pull requests that are directly associated with the given commit
Since in closed PR. the relevant commit is an event type, the backport
automation didn't get the PR info for backporting
Ref: https://github.com/scylladb/scylladb/issues/18973
Closes scylladb/scylladb#21468
(cherry picked from commit ef104b7b96)
Closes scylladb/scylladb#21483