input: Write a function to crawl a given website for specific data such as phone numbers. The function should return a list of found phone numbers in a specified format.
  assert crawl_website_for_phone_numbers('www.example.com')==['123-456-7890', '987-654-3210']
output: def crawl_website_for_phone_numbers(url):
      import re
      import requests
      from bs4 import BeautifulSoup
      
      response = requests.get(url)
      soup = BeautifulSoup(response.text, 'html.parser')
      text = soup.get_text()
      
      phone_numbers = re.findall(r'\d{3}-\d{3}-\d{4}', text)
      
      return phone_numbers