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 branch/default in 1 minute and 9 seconds (queued for 4 seconds)
Status Job ID Name Coverage
  Lint
passed lint_black #82569

00:01:09

passed lint_flake8 #82570

00:00:59