Build

replace `nix-shell` with Nix Flake (#737) #598

Job	Run time
continuous-integration (8.10.7)	9m 51s
continuous-integration (9.0.2)	10m 35s
continuous-integration (9.2.8)	9m 59s
continuous-integration (9.4.5)	10m 3s
continuous-integration (9.6.4)	11m 45s
continuous-integration (9.8.2)	12m 16s
continuous-integration (9.10.1)	8m 39s
continuous-integration (9.12.1, --allow-newer=base --allow-newer=template-haskell --allow-newer=g...	12m 48s
	1h 25m 56s

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