chore: remove magic-nix-cache-action

This is going to stop working at some point in the future, so lets deal
with that now

Author: jamiebrynes7

.github/actions/setup/action.yml

@@ -5,8 +5,6 @@ runs:
   steps:
     - name: Install Nix
       uses: DeterminateSystems/nix-installer-action@main
-    - name: Setup Magic Nix cache
-      uses: DeterminateSystems/magic-nix-cache-action@main
     - name: Use nix-develop shell
       uses: nicknovitski/nix-develop@v1.1.0
       with: