ci: drop magic-nix-cache

The dev shells come from nixpkgs, which cache.nixos.org already serves, so the GitHub Actions cache only added time to each job: starting its daemon, then re-uploading those paths afterwards, often rate-limited. Kept in jobs that run nix build, where it can hold built dependencies.

Author: iamralch

.github/workflows/ci.yml

@@ -24,11 +24,6 @@ jobs:
       - name: Install Nix
         uses: DeterminateSystems/nix-installer-action@v23
 
-      - name: Setup Nix Cache
-        uses: DeterminateSystems/magic-nix-cache-action@v15
-        with:
-          use-flakehub: disabled
-          use-gha-cache: enabled
 
       - name: Install Dependencies
         run: nix develop --command npm ci
@@ -80,11 +75,6 @@ jobs:
       - name: Install Nix
         uses: DeterminateSystems/nix-installer-action@v23
 
-      - name: Setup Nix Cache
-        uses: DeterminateSystems/magic-nix-cache-action@v15
-        with:
-          use-flakehub: disabled
-          use-gha-cache: enabled
 
       - name: Install Dependencies
         run: nix develop --command npm ci

.github/workflows/update.yml

@@ -21,11 +21,6 @@ jobs:
           private-key: ${{ secrets.APP_PRIVATE_KEY }}
       - name: Install Nix
         uses: DeterminateSystems/nix-installer-action@v23
-      - name: Setup Nix Cache
-        uses: DeterminateSystems/magic-nix-cache-action@v15
-        with:
-          use-flakehub: disabled
-          use-gha-cache: enabled
       - name: Update root flake.lock
         uses: DeterminateSystems/update-flake-lock@v29
         with: