remove usage of old external "mock" module

[a-detiste]

Dear Maintainer,

mock has now been merged in the standard library a long time ago,
please consider removing this old external dependency

---

https://github.com/testing-cabal/mock

mock is now part of the Python standard library, available as unittest.mock in Python 3.3 onwards.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (886cb62) to head (de8309d).
Report is 2 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff            @@
##            master       #18   +/-   ##
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  Coverage   100.00%   100.00%           
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  Files            1         1           
  Lines           99        99           
  Branches        25        25           
=========================================
  Hits            99        99           

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[Copilot]

Pull Request Overview

This PR removes the usage of the external "mock" module, switching to the standard library's unittest.mock in tests and updating workflow dependencies accordingly.

• Removed the outdated import of "mock" in tests/test_unordered.py and replaced it with "unittest.mock".
• Updated the GitHub Actions workflows to eliminate installation of the external mock dependency.

Reviewed Changes

Copilot reviewed 2 out of 3 changed files in this pull request and generated no comments.

File	Description
tests/test_unordered.py	Removed external mock import and replaced with unittest.mock
.github/workflows/test.yml	Removed dependency installation of mock/types-mock from workflows

Files not reviewed (1)

• tox.ini: Language not supported