fix Genshin api response data validate

Author: ShiinaRinne

python/stream.py

@@ -22,7 +22,7 @@ class Game(BaseModel):
     id: str
 
 class PreDownload(BaseModel):
-    major: "Major"
+    major: Optional["Major"]
     patches: List["Patch"]
 
 class Main(BaseModel):
@@ -200,4 +200,4 @@ def parse_args():
         os.makedirs(args.output_dir)
 
     asyncio.run(download(urls))
-    
+