Changelogs for 3.12.1.0 (backport #10124)

[mergify]

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Closes #10086

---

This is an automatic backport of pull request #10124 done by [Mergify](https://mergify.com).

[mergify]

Cherry-pick of 2067ed1 has failed:

On branch mergify/bp/master/pr-10124
Your branch is up to date with 'origin/master'.

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Changes to be committed:
	deleted:    changelog.d/issue-10042
	deleted:    changelog.d/issue-10063
	deleted:    changelog.d/issue-6750
	deleted:    changelog.d/issue-8875
	deleted:    changelog.d/issue-9641
	deleted:    changelog.d/issue-9919
	deleted:    changelog.d/issue-9971
	deleted:    changelog.d/pr-10014
	deleted:    changelog.d/pr-9766
	deleted:    changelog.d/pr-9824
	deleted:    changelog.d/pr-9878
	deleted:    changelog.d/pr-9950
	new file:   release-notes/Cabal-3.12.1.0.md
	renamed:    release-notes/WIP-cabal-install-3.12.x.0.md -> release-notes/cabal-install-3.12.1.0.md

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   release-notes/Cabal-3.12.0.0.md

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[geekosaur]

I should probably mention this: worrisomely, master had an entry in Cabal-3.12.0.0.md that wasn't on 3.12 branch.

- Cabal and Cabal-syntax 3.12 support GHC version 8.4.4 and up.

  Support for all previous GHC versions is deprecated.

I merged it into this one, but suspect we need to apply it to 3.12 branch as well.

[ulysses4ever]

@geekosaur we reference changelogs on master, so it's not too bad, perhaps. E.g. https://hackage.haskell.org/package/Cabal-3.12.0.0/changelog

[Mikolaj]

LGTM. I will expedite unless anybody objects, since this is blocking the 3.12.1.0 release.

[Mikolaj]

BTW, the "Cabal and Cabal-syntax 3.12 support GHC version 8.4.4 and up" addition was done as an afterthought in a separate PR on master, because changelogs are used on master, and apparently we forgot to backported this PR or it's languishing unmerged somewhere. No big deal, except that it's unnecessary noise.