setup: Import trubar locally

[janezd]

Issue

Fixes #6992.

Description of changes

Editable install (pip install -e, python setup.py develop) does not run trubar. This PR imports it locally to avoid the unnecessary dependency.

Add-ons already do so. We made a mistake only here.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 88.47%. Comparing base (f3d9e19) to head (8e44908).
Report is 2 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #6997      +/-   ##
==========================================
- Coverage   88.48%   88.47%   -0.01%     
==========================================
  Files         332      332              
  Lines       73296    73296              
==========================================
- Hits        64855    64849       -6     
- Misses       8441     8447       +6     

[markotoplak]

Thanks.

Now I understand how this slipped through. I was only testing editable installs with pip install -e ., which worked properly even with old version (takes care of install dependencies separately).

This PR fixes python setup.py develop