Add support to JupyterLab 2

Signed-off-by: martinRenou <[email protected]>

Author: martinRenou

{{cookiecutter.github_project_name}}/package.json

@@ -49,7 +49,7 @@
     "watch:nbextension": "webpack --watch"
   },
   "dependencies": {
-    "@jupyter-widgets/base": "^1.1.10 || ^2"
+    "@jupyter-widgets/base": "^1.1.10 || ^2 || ^3"
   },
   "devDependencies": {
     "@phosphor/application": "^1.6.0",