Accept code returned when user is already an owner

[gdubicki]

This is a temporary workaround for a idempotency bug
in GitLab.

See issue #361.

[codecov]

Codecov Report

Merging #362 (0bb6c75) into main (db0bf69) will increase coverage by 55.54%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##             main     #362       +/-   ##
===========================================
+ Coverage   25.41%   80.95%   +55.54%     
===========================================
  Files          63       63               
  Lines        2436     2436               
===========================================
+ Hits          619     1972     +1353     
+ Misses       1817      464     -1353     

Impacted Files	Coverage Δ
gitlabform/gitlab/schedules.py	81.25% <ø> (+46.87%)	⬆️
gitlabform/configuration/projects_and_groups.py	100.00% <0.00%> (+15.78%)	⬆️
gitlabform/configuration/groups.py	96.00% <0.00%> (+18.00%)	⬆️
gitlabform/gitlab/commits.py	47.61% <0.00%> (+19.04%)	⬆️
gitlabform/output.py	53.33% <0.00%> (+20.00%)	⬆️
gitlabform/gitlab/project_deploy_keys.py	76.92% <0.00%> (+23.07%)	⬆️
...orm/processors/project/merge_requests_processor.py	25.53% <0.00%> (+25.53%)	⬆️
gitlabform/processors/__init__.py	94.11% <0.00%> (+29.41%)	⬆️
gitlabform/gitlab/projects.py	55.14% <0.00%> (+31.61%)	⬆️
gitlabform/gitlab/project_secret_variables.py	91.66% <0.00%> (+33.33%)	⬆️
... and 44 more