fix: double check that an MR is not wip before assigning

it seems that filtering in the search is not enough, and some MR may be wip,
even when the 'wip="no"' parameter is given.

Let' skip WIP merge requests
2 jobs for topic/default/skip-wip in 1 minute and 6 seconds (queued for 16 seconds)
Status Job ID Name Coverage
  Lint
passed lint_black #72611

00:01:06

passed lint_flake8 #72612

00:00:22