parsing: allow .yml extension

[Paul-weqe]

Although not official recommended YAML extension, .yml extension may still be preferred by some users. This just creates an allowance for that.

[liambrady]

Thanks for the contribution. Please fix the following lint errors (from make ci-lint):

munet/parser.py:105:0: C0301: Line too long (89/88) (line-too-long)
munet/parser.py:115:9: R1714: Consider merging these comparisons with 'in' by using 'ext in ('yaml', 'yml')'. Use a set instead if elements are hashable. (consider-using-in)

[Paul-weqe]

@liambrady Hadn't seen the linting failure.

Done the required changes and ammended them to the commit. It should be ready for review.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 60.48%. Comparing base (58e72ab) to head (e565ff6).
⚠️ Report is 9 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #97      +/-   ##
==========================================
- Coverage   60.62%   60.48%   -0.14%     
==========================================
  Files          19       19              
  Lines        5973     5988      +15     
==========================================
+ Hits         3621     3622       +1     
- Misses       2352     2366      +14     

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[liambrady]

LGTM