[TASK] update Dockerfile

.drone.yml

@@ -14,9 +14,8 @@ steps:
 - name: Run Gulp
   image: gulp-node:${DRONE_COMMIT}
   commands:
-  - which gulp
   - npm install
-  - /usr/local/bin/gulp
+  - gulp
   - zip public.zip dist/*
   
 - name: Upload Artifacts

Scripte/Dockerfile

@@ -1,3 +1,3 @@
 FROM node:12-alpine
 RUN npm install -g gulp
-RUN npm install
+RUN apk install graphicsmagick