ci: cache Nix store with cache-nix-action #2152

Job	Run time
Build Linux (Cabal, GHC 9.0.2)	23m 24s
Build Linux (Cabal, GHC 9.2.4)	23m 52s
Build aarch64 (Cabal, GHC ${{ matrix.ghc }})	0s
Build MacOS (Nix)	12m 40s
Build Linux (Stack)	3m 13s
Build MacOS (Stack)	4m 9s
Build Linux static (Nix)	4m 51s
Build Windows (Stack)	5m 30s
Get FreeBSD build from CirrusCI	5m 14s
Lint & check code style	2m 21s
Test memory (Nix)	4m 48s
Test (Nix)	9m 30s
Test PG 9.6 (Nix)	10m 20s
Test PG 10 (Nix)	7m 46s
Test PG 11 (Nix)	7m 47s
Test PG 12 (Nix)	9m 58s
Test PG 13 (Nix)	7m 36s
Test PG 14 (Nix)	8m 45s
Test PG 15 (Nix)	8m 12s
Test PG 16 (Nix)	10m 43s
Prepare release	0s
Release on GitHub	0s
Release on Docker Hub	0s
Release Arm Builds on Docker Hub	0s
Remove copied files from server	0s
	2h 50m 39s

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