fix: nix caching deprecation

Author: Eveeifyeve

.github/workflows/nix-check.yml

@@ -19,7 +19,7 @@ jobs:
       - uses: actions/checkout@v4
       - name: Install Nix
         uses: DeterminateSystems/nix-installer-action@main
-      - uses: DeterminateSystems/magic-nix-cache-action@main
+      - uses: DeterminateSystems/flakehub-cache-action@main
       - name: Check flake.lock
         uses: DeterminateSystems/flake-checker-action@main
         with:

.github/workflows/update-nix.yml

@@ -14,7 +14,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
       - uses: DeterminateSystems/nix-installer-action@main
-      - uses: DeterminateSystems/magic-nix-cache-action@main
+      - uses: DeterminateSystems/flakehub-cache-action@main 
       - uses: DeterminateSystems/update-flake-lock@main
         with:
           pr-title: "Update flake.lock"