actions/check: log when posting a pending status fails
GitLab does not allow a state transition from pending to pending, so
this may fail if the checks hit an error before the final result has
been decided. Instead of bailing completely and not doing anything if
the pending status cannot be posted, just log the error and continue on.
This specific check being posted is merely for informational purposes
and should not abort the check
action completely.
Unfortunately, there are no mechanisms in the test suite to allow for testing of this code path today.