input: Write a function to post a tweet at a specific hour using the Tweepy library.
  assert post_tweet_at_hour("It's time to wake up!", 17) == "Tweet posted at 17 o'clock"
  assert post_tweet_at_hour("Good morning!", 8) == "Tweet posted at 8 o'clock"
  assert post_tweet_at_hour("Good night!", 22) == "Tweet posted at 22 o'clock"
output: import tweepy
  import time
  from datetime import datetime
  
  def post_tweet_at_hour(tweet, hour):
      # Your authentication credentials
      api_key = "your_api_key"
      api_secret = "your_api_secret"
      access_token = "your_access_token"
      access_token_secret = "your_access_token_secret"
      
      # Authenticate to Twitter
      auth = tweepy.OAuth1UserHandler(api_key, api_secret, access_token, access_token_secret)
      api = tweepy.API(auth)
      
      while True:
          current_hour = datetime.now().hour
          if current_hour == hour:
              api.update_status(tweet)
              return f"Tweet posted at {hour} o'clock"
          time.sleep(60)