Update nix installer action version

Hopefully will get rid of the failures on macos.

Author: michaelpj

.github/workflows/nix.yaml

@@ -19,7 +19,7 @@ jobs:
       - uses: actions/checkout@v3
         with:
           submodules: true
-      - uses: cachix/install-nix-action@v18
+      - uses: cachix/install-nix-action@v22
         with:
           nix_path: nixpkgs=channel:nixos-unstable
       - run: nix-shell --run "cabal update && cabal build all"