[14.0][IMP] update dotfiles

[eantones]

Summary

• Update copier template from v1.11.1 to v1.39
• Migrate CI from Travis CI to GitHub Actions (pre-commit, test, stale)
• Update pre-commit hooks to current versions (black, isort, flake8, eslint, prettier, pylint-odoo, setuptools-odoo)
• Add .gitattributes for merge union on test-requirements.txt
• Update .pylintrc and .pylintrc-mandatory with current checks

Test plan

• CI pre-commit passes
• CI test with Odoo passes
• CI test with OCB passes

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 50.62%. Comparing base (71806b6) to head (1e13ec0).
⚠️ Report is 2 commits behind head on 14.0.

Additional details and impacted files

@@            Coverage Diff             @@
##             14.0     #861      +/-   ##
==========================================
+ Coverage   50.60%   50.62%   +0.01%     
==========================================
  Files         971      971              
  Lines       16406    16406              
  Branches     3496     3496              
==========================================
+ Hits         8303     8306       +3     
+ Misses       7888     7887       -1     
+ Partials      215      213       -2     

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