fix(deps): update dependency through2 to v3 (#209)

Author: renovate[bot]

dialogflow/package.json

@@ -15,7 +15,7 @@
     "dialogflow": "^0.7.0",
     "grpc": "^1.4.1",
     "pump": "^3.0.0",
-    "through2": "^2.0.3",
+    "through2": "^3.0.0",
     "prompt": "^1.0.0",
     "uuid": "^3.3.2",
     "yargs": "^12.0.1"