Fixed a crash when running on CPU and a custom seed was set

app.py

@@ -39,7 +39,10 @@ def error_str(error, title="Error"):
 
 def inference(prompt, guidance, steps, width=512, height=512, seed=0, img=None, strength=0.5, neg_prompt=""):
 
-  generator = torch.Generator('cuda').manual_seed(seed) if seed != 0 else None
+  if torch.cuda.is_available():
+    generator = torch.Generator('cuda').manual_seed(seed) if seed != 0 else None
+  else:
+    generator = torch.Generator.manual_seed(seed) if seed != 0 else None
 
   try:
     if img is not None: