remove buildx and have a better naming

.forgejo/workflows/build.yaml

@@ -12,14 +12,11 @@ env:
 
 jobs:
   build_besu:
-    runs-on: linux-s390x
+    runs-on: ubuntu-24.04-s390x
     steps:
       - name: Checkout code
         uses: actions/checkout@v4
         
-      - name: Set up Docker Buildx
-        uses: docker/setup-buildx-action@v3
-
       - name: Login to gitea registry
         uses: docker/login-action@v3
         with: