Updated woodpecker config to use the electronuserland/builder image to build the app

.woodpecker.yml

@@ -3,7 +3,14 @@ workspace:
   path: app
 
 pipeline:
-  build_linux:
+  build:
+    image: node:16
+    commands:
+      - apt update && apt install -y ruby ruby-dev && gem install sass
+      - npm install
+      - npm run grunt
+
+  package_linux:
     image: electronuserland/builder:16
     commands:
       - npm install