build(npm): remove unused serve-favicon dependency

app.js

@@ -3,7 +3,6 @@ const express = require('express')
 const querystring = require('querystring')
 const path = require('path')
 const helpers = require('./helpers')
-// const favicon = require('serve-favicon')
 const logger = require('morgan')
 const cookieParser = require('cookie-parser')
 const bodyParser = require('body-parser')
@@ -23,8 +22,6 @@ const app = express()
 app.set('views', path.join(__dirname, 'views'))
 app.set('view engine', 'pug')
 
-// uncomment after placing your favicon in /public
-// app.use(favicon(path.join(__dirname, 'public', 'favicon.ico')));
 app.use(logger('dev'))
 app.use(bodyParser.json())
 app.use(bodyParser.urlencoded({ extended: false }))