Fix CI

.github/workflows/sync-channels.yaml

@@ -30,6 +30,8 @@ jobs:
 
     - name: Install Nix
       uses: cachix/install-nix-action@v16
+      with:
+        nix_path: nixpkgs=channel:nixpkgs-unstable
 
     - name: Sync stable channel
       timeout-minutes: 5
@@ -61,12 +63,6 @@ jobs:
           nix-instantiate --parse "${files[@]}" >/dev/null
         fi
 
-    - name: Install Nix
-      if: steps.commit.outcome == 'success'
-      uses: cachix/install-nix-action@v16
-      with:
-        nix_path: nixpkgs=channel:nixpkgs-unstable
-
     - name: Test stable Rust
       if: steps.commit.outcome == 'success'
       run: |