Ruff hotfix

[henrydingliu]

Summary of Changes

fixing ruff violations somehow left by #1205

Related GitHub Issue(s)

Additional Context for Reviewers

Checklist

• I passed tests locally for both code (uv run pytest) and documentation changes (uv run --directory docs jb build . --builder=custom --custom-builder=doctest)

---

Note

Low Risk
Cosmetic formatting only; no logic or API changes beyond style.

Overview
Follow-up to #1205: Ruff-only cleanup in chainladder/utils/utility_functions.py with no intended behavior change.

Updates include PEP 484-style spacing in model_diagnostics annotations (| unions), comma spacing in hasattr calls, keyword-argument formatting on align_pattern (sample_weight=...), and whitespace inside f-strings built by PTF_formula (index/subtraction and division around graingamma / iota knots).

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[github-actions]

Pyright Type Completeness

View the full pyright --verifytypes output for this commit

Project (full chainladder package, at this PR's head): 15.1% of exported symbols fully typed (202 / 1336)

	Known	Ambiguous	Unknown	Total
Project (head)	202	111	1023	1336

Other symbols referenced but not exported by chainladder: 13

	Known	Ambiguous	Unknown	Total
Other (head)	3	1	9	13

Symbols without documentation:

• Functions without docstring: 323
• Functions without default param: 0
• Classes without docstring: 10

Patch (exported symbols added or changed by this PR): no exported symbol type-completeness changes detected.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.27%. Comparing base (558274f) to head (beec479).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1217   +/-   ##
=======================================
  Coverage   91.27%   91.27%           
=======================================
  Files          91       91           
  Lines        5411     5411           
  Branches      692      692           
=======================================
  Hits         4939     4939           
  Misses        338      338           
  Partials      134      134           

Flag	Coverage Δ
unittests	91.27% <100.00%> (ø)

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