input: Write a python function to handle a POST request with JSON data using Flask and print the payload.
  assert webhook().status_code == 200
output: from flask import Flask, request, jsonify
  
  app = Flask(__name__)
  
  @app.route('/webhook', methods=['POST'])
  def webhook():
      data = request.json
      print(data)
      return jsonify(success=True), 200
  
  if __name__ == '__main__':
      app.run(debug=True)