Update gitpod configuration

.gitpod.Dockerfile

@@ -0,0 +1,2 @@
+FROM gitpod/workspace-full
+RUN sudo apt-get update && sudo apt-get install -y libgtk-3-0 libx11-xcb1 libnss3 libxss1 libasound2

.gitpod.yml

@@ -1,7 +1,9 @@
+image:
+  file: .gitpod.Dockerfile
 tasks:
   - command: gp await-port 3000 && sleep 3 && gp preview $(gp url 3000)/examples/browser/demo.html
   - init: npm install
     command: npm start
 ports:
   - port: 3000
-    onOpen: ignore
+    onOpen: ignore