ci: cache Nix store with cache-nix-action #2039

Job	Run time
Build MacOS (Nix)	10m 58s
Build Linux (Stack)	3m 37s
Build Linux (Cabal, GHC 9.0.2)	27m 1s
Build MacOS (Stack)	5m 26s
Build Linux static (Nix)	3m 5s
Build Linux (Cabal, GHC 9.2.4)	19m 45s
Build Windows (Stack)	6m 1s
Get FreeBSD build from CirrusCI	5s
Lint & check code style	1m 42s
Test memory (Nix)	3m 48s
Test (Nix)	9m 1s
Test PG 9.6 (Nix)	7m 14s
Build aarch64 (Cabal, GHC ${{ matrix.ghc }})	0s
Test PG 10 (Nix)	7m 7s
Test PG 11 (Nix)	7m 45s
Test PG 12 (Nix)	7m 32s
Test PG 13 (Nix)	8m 15s
Test PG 14 (Nix)	7m 15s
Test PG 15 (Nix)	7m 51s
Test PG 16 (Nix)	7m 42s
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
	2h 31m 10s

Provide feedback