Thank you for your reply.

self.gru = nn.GRU(hidden_size, hidden_size, n_layers, dropout=(0 if n_layers == 1 else dropout), bidirectional=True)

original.

self.lstm = nn.LSTM(hidden_size, hidden_size, n_layers, dropout=(0 if n_layers == 1 else dropout), bidirectional=True)

swapped to LSTM.
The only thing that I change was nn.GRU to nn.LSTM for both EncoderRNN and LuongAttnDecoderRNN.
Original Code Link: https://pytorch.org/tutorials/beginner/chatbot_tutorial.html 26