Correct Transformer2DModel.forward docstring (#3074)

⚙️chore(transformer_2d) update function signature for encoder_hidden_states

Author: offchan42

src/diffusers/models/transformer_2d.py

@@ -225,7 +225,7 @@ def forward(
             hidden_states ( When discrete, `torch.LongTensor` of shape `(batch size, num latent pixels)`.
                 When continuous, `torch.FloatTensor` of shape `(batch size, channel, height, width)`): Input
                 hidden_states
-            encoder_hidden_states ( `torch.LongTensor` of shape `(batch size, encoder_hidden_states dim)`, *optional*):
+            encoder_hidden_states ( `torch.FloatTensor` of shape `(batch size, sequence len, embed dims)`, *optional*):
                 Conditional embeddings for cross attention layer. If not given, cross-attention defaults to
                 self-attention.
             timestep ( `torch.long`, *optional*):