ci: cache Nix store with cache-nix-action #2169

Job	Run time
Test (Nix)	10m 8s
Lint & check code style	2m 33s
Test PG 9.6 (Nix)	9m 46s
Test PG 10 (Nix)	9m 19s
Build Linux (Cabal, GHC 9.0.2)	22m 21s
Test PG 11 (Nix)	9m 1s
Build Linux (Cabal, GHC 9.2.4)	26m 42s
Build MacOS (Nix)	10m 34s
Test PG 12 (Nix)	7m 29s
Test PG 13 (Nix)	9m 12s
Build Linux (Stack)	24m 18s
Test PG 14 (Nix)	8m 53s
Build Linux static (Nix)	4m 0s
Build MacOS (Stack)	32m 14s
Test PG 15 (Nix)	7m 40s
Build Windows (Stack)	37m 29s
Test PG 16 (Nix)	9m 13s
Get FreeBSD build from CirrusCI	12s
Test memory (Nix)	4m 5s
Build aarch64 (Cabal, GHC ${{ matrix.ghc }})	0s
Prepare release	0s
Release on Docker Hub	0s
Release on GitHub	0s
Release Arm Builds on Docker Hub	0s
Remove copied files from server	0s
	4h 5m 9s

Provide feedback