add github action to assign milestone automatically

[seanbudd]

Link to issue number:

None

Summary of the issue:

NV Access has a server side script to automatically assign milestones to closed issues and PRs. This script has been malfunctioning for some time meaning we are not tracking which release issues are closed in.

Description of user facing changes

Description of development approach

Used copilot to generate a github action to assign milestones

Testing strategy:

• [ ] TODO test on another repo

Known issues with pull request:

• [ ] Need to update internal release docs to ensure the milestone id is updated when starting the release cycle
• [ ] need to tear out dead automilestone script

Code Review Checklist:

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

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