add typescript as a dev dependency

Author: phryneas

package.json

@@ -73,6 +73,7 @@
     "prop-types": "15.7.2",
     "react": "16.10.2",
     "react-dom": "16.10.2",
-    "storybook-chromatic": "3.0.3"
+    "storybook-chromatic": "3.0.3",
+    "typescript": "3.6.4"
   }
 }