missing 'steps' in build.yml

Author: mikeshulman

.github/workflows/build.yml

@@ -7,6 +7,7 @@ on:
 jobs:
   test:
     runs-on: ubuntu-latest
+    steps:
     - uses: actions/checkout@v4
     - uses: DeterminateSystems/nix-installer-action@main
     - run: nix profile install nixpkgs#cachix