Update nixpkgs pins #2017

Job	Run time
cabal	20s
cabal-doExactConfig	17s
runghc	17s
nix-build	1h 6m 22s
unit-tests	5s
build-extra-hackages	16s
maintainer-scripts	14s
multi-target	2m 4s
plan-extra-hackages	5s
shellFor-hoogle	9s
shellFor-not-depends	14s
shellFor-multiple-package	27s
shellFor-single-package	16s
tests-benchmarks	13s
docs	31s
hix	1h 4m 58s
hydra-ifdLevel-0-and-1	18s
hydra-ifdLevel-2	18s
hydra-ifdLevel-3-and-ghc-8-10	13s
hydra-ifdLevel-3-and-ghc-9-2	16s
hydra-ifdLevel-3-and-not-ghc-8-10-or-9-2	18s
check-materialization-concurrency	22s
check-path-support	10s
closure-size	12s
haskell-nix-roots-do-not-require-IFDs	10s
hix-cabal	1h 4m 25s
hydra-without-remote-builders	3m 32s
nix-tools	58s
update-docs	14s
	3h 28m 14s

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