Do not close the request webhook issue if there is a problem

Cc @daniels

See fdo-bots#19 (comment 1843376)

Too many requests at the same time, and instead of retrying in case of a fail push, we just fail and close the issue leaving the user clueless on what should be done.

We should at least have a better comment here, and explain that the request needs to be postponed and retried later.