Removed predict return types

The specified return types were overly resetrictive (e.g. did not include sequence labelling models)

flair/nn/model.py

@@ -817,7 +817,7 @@ def predict(
         label_name: Optional[str] = None,
         return_loss: bool = False,
         embedding_storage_mode: EmbeddingStorageMode = "none",
-    ) -> Optional[Union[list[DT], tuple[float, int]]]:
+    ):
         """Predicts the class labels for the given sentences. The labels are directly added to the sentences.
 
         Args: