Improve typing of tests

[gerlero]

No description provided.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (5e2e395) to head (e5932ca).

Additional details and impacted files

@@            Coverage Diff            @@
##              main       #85   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            3         3           
  Lines          352       352           
=========================================
  Hits           352       352           

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[Copilot]

Pull Request Overview

This PR improves type annotations in the multicollections test file by replacing generic MutableMultiMapping type hints with specific union types for the actual classes being tested. The changes remove the need for # type: ignore[call-arg] comments throughout the test file by providing more accurate type information.

Key changes:

• Replace MutableMultiMapping[K, V] type annotations with specific unions like MultiDict[K, V] | ListMultiDict[K, V] | multidict.MultiDict[V]
• Remove # type: ignore comments that are no longer needed due to improved typing
• Fix a type annotation inconsistency in one test function parameter

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