Prepare release: 8.4.1

[github-actions]

⚡ Merging this PR will automatically create a GitHub Release & publish the package ⚡

This PR was created by the Release stage 1 - create release PR (Cylc 8+ only) workflow, triggered by @oliver-sanders

Tests:

• Tests last run on 8.4.x:
  
  
  
  
  
• ✔️ Build check passed - see the workflow run (number 47) for more info

Checklist:

• Milestone complete?
  0 other open issues/PRs on milestone 8.4.1 at time of PR creation

Next steps:

• @oliver-sanders should request 1 or 2 reviews
• If any further changes are needed, push to this PR branch
• After merging, the bot will comment below with a link to the release (if not, look at the PR checks tab)

Important

Do not use [skip ci] in commit messages pushed to this PR, as it will prevent the 2nd stage release workflow from running.

[github-actions]

✔️ success

Next steps for @oliver-sanders:

• view/edit the GitHub release description as appropriate
• ✔️ Milestone automatically closed

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Comment created by workflow: Release stage 2 - auto publish, run: 98