fix: update merge job to specify self-hosted runner architecture

Author: chvvkumar

.github/workflows/snd.yml

@@ -75,7 +75,7 @@ jobs:
   merge:
     name: Merge Multi-Arch Image
     needs: build
-    runs-on: [self-hosted, Linux]
+    runs-on: [self-hosted, Linux, X64]
     steps:
       - name: Login to Docker Hub
         uses: docker/login-action@v3