[Flax SD finetune] Fix dtype (#1038)

fix jnp dtype

examples/text_to_image/train_text_to_image_flax.py

@@ -371,11 +371,11 @@ def main():
         train_dataset, shuffle=True, collate_fn=collate_fn, batch_size=total_train_batch_size, drop_last=True
     )
 
-    weight_dtype = torch.float32
+    weight_dtype = jnp.float32
     if args.mixed_precision == "fp16":
-        weight_dtype = torch.float16
+        weight_dtype = jnp.float16
     elif args.mixed_precision == "bf16":
-        weight_dtype = torch.bfloat16
+        weight_dtype = jnp.bfloat16
 
     # Load models and create wrapper for stable diffusion
     tokenizer = CLIPTokenizer.from_pretrained(args.pretrained_model_name_or_path, subfolder="tokenizer")