fix: Fixed TransformerDecoder for PyTorch 1.10 (#539)

doctr/models/recognition/transformer/pytorch.py

@@ -59,6 +59,7 @@ def __init__(
                 dim_feedforward=dff,
                 dropout=dropout,
                 activation='relu',
+                batch_first=True,
             ) for _ in range(num_layers)
         ])
 
@@ -79,13 +80,11 @@ def forward(
         x += self.pos_encoding[:, :seq_len, :]
         x = self.dropout(x)
 
-        # Batch first = False in decoder
-        x = x.permute(1, 0, 2)
+        # Batch first = True in decoder
         for i in range(self.num_layers):
             x = self.dec_layers[i](
                 tgt=x, memory=enc_output, tgt_mask=look_ahead_mask, memory_mask=padding_mask
             )
 
         # shape (batch_size, target_seq_len, d_model)
-        x = x.permute(1, 0, 2)
         return x