Unpin and bump fsevents (for 1.x branch) (facebook#4006)

Author: gaearon

package.json

@@ -64,6 +64,6 @@
     "react-dom": "^16.0.0"
   },
   "optionalDependencies": {
-    "fsevents": "1.1.2"
+    "fsevents": "^1.1.3"
   }
 }