input: Write a function to generate a random number between given min and max using Flask.
  assert isinstance(generate_random_number(1, 10), str)
  assert isinstance(generate_random_number(20, 30), str)
  assert isinstance(generate_random_number(100, 200), str)
output: from flask import Flask, jsonify
  import random
  
  app = Flask(__name__)
  
  @app.route('/random/<int:min>/<int:max>', methods=['GET'])
  def generate_random_number(min, max):
      random_number = random.randint(min, max)
      return jsonify({'random_number': random_number})