fix(workflow): update cachix action version to v31

Author: soulomoon

.github/workflows/format.yaml

@@ -1,6 +1,6 @@
 name: Format
 
-on: 
+on:
   push:
     branches:
       - master
@@ -12,7 +12,7 @@ jobs:
 
     steps:
       - uses: actions/checkout@v3
-      - uses: cachix/install-nix-action@v22
+      - uses: cachix/install-nix-action@v31
         with:
           nix_path: nixpkgs=channel:nixos-unstable
       - run: nix-shell --run "fourmolu -m check ."

.github/workflows/nix.yaml

@@ -1,6 +1,6 @@
 name: Nix
 
-on: 
+on:
   push:
     branches:
       - master
@@ -17,7 +17,7 @@ jobs:
 
     steps:
       - uses: actions/checkout@v3
-      - uses: cachix/install-nix-action@v22
+      - uses: cachix/install-nix-action@v31
         with:
           nix_path: nixpkgs=channel:nixos-unstable
       - run: nix-shell --run "cabal update && cabal build all"