remove wheel preference, add CI

.github/workflows/nix-fmt.yml

@@ -0,0 +1,25 @@
+name: "Check Nix formatting"
+on:
+    push:
+        branches: ["main"]
+    pull_request:
+        branches: ["main"]
+    merge_group:
+jobs:
+    health-check:
+        name: "Perform Nix format checks"
+        runs-on: ubuntu-latest
+        steps:
+            - uses: DeterminateSystems/nix-installer-action@main
+            - name: Setup Attic cache
+              uses: ryanccn/attic-action@v0
+              with:
+                endpoint: ${{ secrets.ATTIC_ENDPOINT }}
+                cache: ${{ secrets.ATTIC_CACHE }}
+                token: ${{ secrets.ATTIC_TOKEN }}
+                skip-push: "true"
+            - uses: actions/checkout@v4
+            - run: nix fmt -- --check .
+            - name: Push to Attic
+              run: nix ./utils/attic-push.bash
+              continue-on-error: true