Update app.py

app.py

@@ -14,7 +14,7 @@ def create_issue(
     owner_repo: str,
     title: str,
     body: str,
-    github_token: str = "",   # ← デフォルト値を追加
+    github_token: Optional[str] = None,
     request: gr.Request = None
 ) -> str:
     """