Update unit testing documentation

[SaschaCowley]

Link to issue number:

None

Summary of the issue:

The current documentation for running unit tests is out of date, referring to tools that we no longer use, and commands that no longer work.

Description of user facing changes

Updated the project documentation to reflect the status quo.

Description of development approach

N/A

Testing strategy:

Ran any command line examples to ensure they work as expected.

Known issues with pull request:

None

Code Review Checklist:

• [x] Documentation:
  • Change log entry
  • User Documentation
  • Developer / Technical Documentation
  • Context sensitive help for GUI changes
• [x] Testing:
  • Unit tests
  • System (end to end) tests
  • Manual testing
• [x] UX of all users considered:
  • Speech
  • Braille
  • Low Vision
  • Different web browsers
  • Localization in other languages / culture than English
• [x] API is compatible with existing add-ons.
• [x] Security precautions taken.

Summary by CodeRabbit

• Documentation
  • Enhanced unit testing instructions, detailing how to run specific tests using patterns with the -k option.
  • Updated documentation to reflect the use of xmlrunner for test execution, improving clarity on argument forwarding.