ci: Use mlugg's setup-zig workflow

.github/workflows/test.yml

@@ -8,12 +8,11 @@ jobs:
         uses: actions/checkout@v4
       - run: |
           apt update; apt install --yes sudo
-      - uses: https://github.com/cachix/install-nix-action@v30
+      - uses: https://github.com/mlugg/setup-zig@v1
         with:
-          nix_path: nixpkgs=channel:nixos-unstable
-          enable_kvm: false
+          version: master
 
       # Cross-compile the binary. We always use static building for this
       # because its the only way to access the headers.
       - name: Test
-        run: nix develop -c zig build test --summary all
+        run: zig build test --summary all