Fix broken dev shell build

.github/workflows/build.yaml

@@ -32,11 +32,13 @@ jobs:
       - uses: actions/checkout@v3
       - uses: DeterminateSystems/nix-installer-action@main
       - uses: DeterminateSystems/magic-nix-cache-action@main
-      - name: Build package
-        run: |
-          # Cache dev shell
-          nix build .#devShells.${{ matrix.systems.nix-system }}
 
+      - name: Build and cache dev shell
+        run: |
+          nix build ".#devShells.${{ matrix.systems.nix-system }}.default"
+
+      - name: Build package and create closure
+        run: |
           nix build .# -L --fallback && nix-store --export $(nix-store -qR ./result) | xz -9 > "${{ env.CLOSURE_FILE }}"
 
       - name: Upload a Build Artifact