fix(traceback): highlight win32 paths

[abesto]

Type of changes

• [x] Bug fix
• [ ] New feature
• [ ] Documentation / docstrings
• [x] Tests
• [ ] Other

Checklist

• [x] I've run the latest black with default args on new code.
• [x] I've updated CHANGELOG.md and CONTRIBUTORS.md where appropriate.
• [x] I've added tests for new code.
• [x] I accept that @willmcgugan may be pedantic in the code review.

Description

PathHighlighter uses a regex to parse paths for highlighting. It used / as the final path component delimiter. This PR changes that to "either / or \".

I toyed with using os.path.sep, but there's no reason to not highlight paths from other OSes than the one we're running on at the moment.

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Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 97.98%. Comparing base (45cc90b) to head (54d224f). Report is 83 commits behind head on master.

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Additional details and impacted files

@@           Coverage Diff           @@
##           master    #3734   +/-   ##
=======================================
  Coverage   97.98%   97.98%           
=======================================
  Files          74       74           
  Lines        8142     8142           
=======================================
  Hits         7978     7978           
  Misses        164      164           

Flag	Coverage Δ
unittests	97.98% <100.00%> (ø)

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