Prepare release: 8.2.3

[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 @markgrahamdawson

Tests:

• Tests last run on 8.2.x:
• ✔️ Build check passed - see the workflow run (number 29) for more info

Checklist:

• Milestone complete?
  0 other open issues/PRs on milestone cylc-8.2.3 at time of PR creation
• Changelog up-to-date?
  • Examine pull requests made since the last release
  • "Released on" date updated? ⚠️ couldn't automatically set date

Next steps:

• @markgrahamdawson 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)

[MetRonnie]

Just re-running https://github.com/cylc/cylc-flow/actions/runs/6732022396/job/18308294626 (chunk 4/4) for peace of mind

[oliver-sanders]

(merge when test happy)

[github-actions]

✔️ success

Next steps for @markgrahamdawson:

• 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: 64