Update nixpkgs pins #2573

Job	Run time
build-extra-hackages	15s
cabal	1m 55s
cabal-doExactConfig	1m 52s
docs	23s
hix	1h 28m 54s
maintainer-scripts	8s
multi-target	25m 19s
nix-build	1h 32m 45s
plan-extra-hackages	22s
runghc	19s
shellFor-hoogle	22m 33s
shellFor-multiple-package	57m 8s
shellFor-not-depends	30s
shellFor-single-package	20s
tests-benchmarks	42m 53s
unit-tests	18s
check-materialization-concurrency	31s
check-path-support	42s
closure-size	8s
haskell-nix-roots-do-not-require-IFDs	1h 7m 28s
hix-cabal	1h 14m 34s
hydra-ifdLevel-0-and-1	5m 56s
hydra-ifdLevel-2	2m 33s
hydra-ifdLevel-3	44s
hydra-without-remote-builders-ghc8107	9s
hydra-without-remote-builders-ghc9101	6s
nix-tools	7m 26s
update-docs	1m 46s
	8h 17m 57s

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