Remove Nix caching that can't work due to /nix/store permissions

.gitea/workflows/test-and-build.yml

@@ -28,16 +28,6 @@ jobs:
           restore-keys: |
             cabal-
 
-      - name: Set up cache for Nix
-        uses: actions/cache@v4
-        with:
-          path: |
-            /nix/store
-            /nix/var/nix/cache
-          key: nix-${{ hashFiles('flake.lock') }}
-          restore-keys: |
-            nix-
-
       - name: Initialize Cabal and update package list
         run: |
           nix develop --command cabal update
@@ -58,16 +48,6 @@ jobs:
         with:
           fetch-depth: 0
 
-      - name: Set up cache for Nix
-        uses: actions/cache@v4
-        with:
-          path: |
-            /nix/store
-            /nix/var/nix/cache
-          key: nix-${{ hashFiles('flake.lock') }}
-          restore-keys: |
-            nix-
-  
       - name: Build and shrink binary
         run: |
           nix build