Release 3.12.1.0 version bumps

[geekosaur]

The original branch name collides with a branch protection rule, making it difficult to work with.
This is C.3.1/2 in the wiki.
See #9885.

[ulysses4ever]

As an experiment, I'd try to change:

cabal/cabal-testsuite/cabal-testsuite.cabal

Lines 149 to 150 in 06145ea

	setup-depends: Cabal == 3.10.*,
	Cabal-syntax == 3.10.*,

to say 3.12 instead of 3.10.

[geekosaur]

Yeh, I changed it back and it worked locally, so I tried to push it up and discovered that I'd misnamed my local branch and branch protections were applying on github's side. So I killed the branch and started over.

[geekosaur]

Unrequested reviews until I finish with bootstrap plans.

[ulysses4ever]

LGTM, thank you!

[geekosaur]

I'm not actually sure it's ready though. We don't have a 9.10.1 bootstrap, and I'm still suspicious that hackage-security isn't actually using the correct Cabal/Cabal-syntax.

[geekosaur]

Right, I just tried to add a 9.10.1 bootstrap and ran into one of the known upstream issues (TH version) which I think is fixed in git but not yet released.

[geekosaur]

Sorry, wrong ticket

[geekosaur]

haskell/hackage-security#316

[geekosaur]

I'll hold onto the changes for 9.10.1 bootstrap and apply them to master when hackage-security is ready.

[geekosaur]

Manual squash+merge because Mergify on 3.12 has neither squash+merge me nor rules for non-backports on non-master branches. I'll fix both post-release.