Fix #72 get-audio-duration dependency should be in kitchensink package.json (#73)

Author: micksatana

examples/kitchensink/package-lock.json

@@ -8,6 +8,7 @@
   },
   "dependencies": {
     "@line/bot-sdk": "^5.0.0",
-    "express": "^4.16.2"
+    "express": "^4.16.2",
+    "get-audio-duration": "0.0.1"
   }
 }