input: Write a python function to determine the winner of a rock-paper-scissors game based on player and computer moves.
  assert determine_winner("rock", "scissors") == "You win!"
  assert determine_winner("rock", "paper") == "Computer wins!"
  assert determine_winner("rock", "rock") == "It's a tie!"
  assert determine_winner("paper", "scissors") == "Computer wins!"
  assert determine_winner("paper", "rock") == "You win!"
  assert determine_winner("scissors", "rock") == "Computer wins!"
  assert determine_winner("scissors", "paper") == "You win!"
output: def determine_winner(player_move, computer_move):
      if player_move == computer_move:
          return "It's a tie!"
      elif (player_move == "rock" and computer_move == "scissors") or \
           (player_move == "paper" and computer_move == "rock") or \
           (player_move == "scissors" and computer_move == "paper"):
          return "You win!"
      else:
          return "Computer wins!"