ci: remove remaining input-output-hk/install-nix-action

Author: johnalotoski

.github/workflows/actionlint.yml

@@ -14,15 +14,12 @@ jobs:
       # its own shellcheck. This will also make sure that this pipeline runs using
       # the same shellcheck as the ones in Nix shells of developers.
       - name: Install Nix with good defaults
-        uses: input-output-hk/install-nix-action@v20
+        uses: cachix/install-nix-action@v31
         with:
           extra_nix_config: |
             trusted-public-keys = cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY= hydra.iohk.io:f/Ea+s+dFdN+3Y/G+FDgSq+a5NEWhJGzdjvKNGv0/EQ=
             substituters = https://cache.nixos.org/ https://cache.iog.io/
           nix_path: nixpkgs=channel:nixos-unstable
-      - uses: cachix/install-nix-action@v18
-        with:
-          nix_path: nixpkgs=channel:nixos-unstable
       # Make the Nix environment available to next steps
       - uses: rrbutani/use-nix-shell-action@v1
 

.github/workflows/shellcheck.yml

@@ -16,15 +16,12 @@ jobs:
     steps:
       - uses: actions/checkout@v4
       - name: Install Nix with good defaults
-        uses: input-output-hk/install-nix-action@v20
+        uses: cachix/install-nix-action@v31
         with:
           extra_nix_config: |
             trusted-public-keys = cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY= hydra.iohk.io:f/Ea+s+dFdN+3Y/G+FDgSq+a5NEWhJGzdjvKNGv0/EQ=
             substituters = https://cache.nixos.org/ https://cache.iog.io/
           nix_path: nixpkgs=channel:nixos-unstable
-      - uses: cachix/install-nix-action@v18
-        with:
-          nix_path: nixpkgs=channel:nixos-unstable
       # Make the Nix environment available to next steps
       - uses: rrbutani/use-nix-shell-action@v1
       - name: shellcheck