fix: 修改设备选择逻辑，支持在没有 CUDA 的情况下使用 CPU

app.py

@@ -68,12 +68,16 @@ class Demo:
 
         self.training = False
         self.generating = False
-        self.device = 'cuda'
         self.weight_dtype = torch.bfloat16
         self.model_sections = []
         self.model_sections_count = gr.State(0)
         
         model_id = 'stabilityai/stable-diffusion-xl-base-1.0'
+        if torch.cuda.is_available():
+            self.device = 'cuda'
+        else:
+            self.device = 'cpu'
+
         pipe = StableDiffusionXLPipeline.from_pretrained(model_id, torch_dtype=self.weight_dtype).to(self.device)
         pipe = None
         del pipe