Add ghc-9.14 language extensions

[philderbeast]

Fixes #11635. I made similar changes to #10339. The test is the updated md5 check.

Important

Will this need a backport?

---

• Patches conform to the coding conventions.
• Any changes that could be relevant to users have been recorded in the changelog.
  • Is the change significant? If so, remember to add significance: significant in the changelog file.
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[geekosaur]

I'm inclined to say yes, since it's arguably a bug fix for the cabal version intended to support 9.14.

Also, this is a step in the release documentation. What went wrong, fellow cabalers?

[Bodigrim]

Will this need a backport?

Absolutely.

[mergify]

Merge Queue Status

• ✅ Entered queue — 2026-03-28 14:31 UTC · Rule: default
• ✅ Checks passed · on draft merge queue: embarking master (87b87bc) and #11636 together #11670
• ✅ Merged — 2026-03-28 16:29 UTC · at 1dd4ffd76e1fc7569f1a4aa26d46e2b93daf534e

This pull request spent 1 hour 58 minutes 4 seconds in the queue, including 1 hour 47 minutes 25 seconds running CI.

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[ffaf1]

We missed the backport for this.
No worries, I did it in one swoop with #11962

(It misses a changelog too!)