Add GHC 9.12.1 #2846

Job	Run time
nix-build	5m 3s
runghc	39s
cabal	38s
unit-tests	29s
build-extra-hackages	2m 35s
cabal-doExactConfig	34s
maintainer-scripts	9s
multi-target	55s
plan-extra-hackages	1m 56s
shellFor-hoogle	16s
shellFor-multiple-package	19s
shellFor-not-depends	13s
shellFor-single-package	20s
tests-benchmarks	2m 2s
check-materialization-concurrency	19s
check-path-support	11s
closure-size	3s
docs	25s
haskell-nix-roots-do-not-require-IFDs	11s
hix	6m 8s
hydra-ifdLevel-0-and-1	4m 48s
hydra-ifdLevel-2	5m 59s
hydra-ifdLevel-3	14m 57s
hydra-without-remote-builders-ghc8107	2m 57s
hydra-without-remote-builders-ghc9101	2m 25s
update-docs	4s
hix-cabal	3m 15s
nix-tools	1m 21s
	59m 11s

Provide feedback