fix(package): update through2 to version 2.0.4

Author: greenkeeper[bot]

package.json

@@ -33,7 +33,7 @@
     "moment": "2.22.2",
     "plugin-error": "1.0.1",
     "q": "1.5.1",
-    "through2": "2.0.3"
+    "through2": "2.0.4"
   },
   "devDependencies": {
     "@babel/core": "7.1.2",