[yt-dlp] Fix YoutubeDL.YoutubeDL.download return value (#15336)

Author: Tatsh

stubs/yt-dlp/yt_dlp/YoutubeDL.pyi

@@ -89,7 +89,7 @@ class YoutubeDL:
     def dl(self, name: str, info: _InfoDict, subtitle: bool = False, test: bool = False) -> bool: ...
     def existing_file(self, filepaths: Iterable[str], *, default_overwrite: bool = True) -> str | None: ...
     def process_info(self, info_dict: _InfoDict) -> None: ...
-    def download(self, url_list: Collection[str]) -> None: ...
+    def download(self, url_list: Collection[str]) -> int: ...
     def download_with_info_file(self, info_filename: str) -> int: ...
     @staticmethod
     def sanitize_info(info_dict: _InfoDict, remove_private_keys: bool = False) -> _InfoDict | None: ...