Update nixpkgs pins #2038

Job	Run time
cabal-doExactConfig	1m 30s
cabal	1m 34s
nix-build	4m 16s
runghc	1m 35s
tests-benchmarks	1m 20s
unit-tests	33s
build-extra-hackages	1m 21s
check-materialization-concurrency	18s
check-path-support	28s
closure-size	4s
docs	1m 12s
haskell-nix-roots-do-not-require-IFDs	7s
hix	5m 46s
hix-cabal	36m 21s
hydra-ifdLevel-0-and-1	29s
hydra-ifdLevel-2	20s
hydra-ifdLevel-3-and-ghc-8-10	18s
hydra-ifdLevel-3-and-ghc-9-2	20s
hydra-ifdLevel-3-and-not-ghc-8-10-or-9-2	7s
hydra-without-remote-builders	32s
multi-target	2m 42s
maintainer-scripts	10s
nix-tools	14s
plan-extra-hackages	8s
shellFor-hoogle	1m 31s
shellFor-multiple-package	2m 18s
shellFor-not-depends	11s
shellFor-single-package	1m 38s
update-docs	5s
	1h 7m 28s

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