fix(package): update form-data to version 2.3.1

Author: greenkeeper[bot]

package.json

@@ -16,7 +16,7 @@
   "dependencies": {
     "@types/node": "8.0.24",
     "es6-promise": "4.1.1",
-    "form-data": "2.2.0",
+    "form-data": "2.3.1",
     "isomorphic-fetch": "2.2.1",
     "object-assign": "4.1.1",
     "workfront-api-constants": "2.0.0"