修复类型注解

konabot/plugins/roll_dice/roll_dice.py

@@ -334,7 +334,8 @@ async def generate_dice_image(number: str) -> BytesIO:
     move_distance = (up_direction[0] * (stretch_k - 1), up_direction[1] * (stretch_k - 1))
 
     # 加载背景图像，保留透明通道
-    background = cv2.imread(ASSETS_PATH / "img" / "dice" / "template.png", cv2.IMREAD_UNCHANGED)
+    background = cv2.imread(str(ASSETS_PATH / "img" / "dice" / "template.png"), cv2.IMREAD_UNCHANGED)
+    assert background is not None
 
     height, width = background.shape[:2]