Update .drone.yml

.drone.yml

@@ -8,6 +8,12 @@ platform:
   arch: amd64
 
 steps:
+  - name: Build JS/CSS
+    image: node:current-slim
+    commands:
+      - yarn set version stable
+      - yarn install
+      - yarn build
   - name: Ubuntu 22.04
     image: ubuntu:jammy
     commands: