Fix missing dependencies

Author: fcollonval

toolbar-button/package.json

@@ -46,7 +46,11 @@
     "watch:src": "tsc -w"
   },
   "dependencies": {
-    "@jupyterlab/application": "^3.0.11"
+    "@jupyterlab/application": "^3.0.11",
+    "@jupyterlab/apputils": "^3.0.9",
+    "@jupyterlab/docregistry": "^3.0.11",
+    "@jupyterlab/notebook": "^3.0.11",
+    "@lumino/disposable": "^1.7.0"
   },
   "devDependencies": {
     "@jupyterlab/builder": "^3.0.0",
@@ -71,4 +75,4 @@
     "extension": true,
     "outputDir": "jupyterlab_examples_toolbar_button/labextension"
   }
-}
+}