set four hour timeout for risc build

Author: altendky

.github/workflows/build-ubuntu-22.04-risc.yml

@@ -23,6 +23,7 @@ concurrency:
 jobs:
   build:
     uses: Chia-Network/actions/.github/workflows/docker-build.yaml@main
+    timeout-minutes: 240
     with:
       alternate-latest-mode: true
       runs-on: k8s-public