ci: debug with tmate

Author: mrpollo

.github/workflows/test_build_qemu_arm64.yml

@@ -35,4 +35,5 @@ jobs:
           kas build kas/sgl-scarthgap-qemuarm64.yml
 
       - name: Setup tmate session
+        if: ${{ failure() }}
         uses: mxschmitt/action-tmate@v3