explicitly&correctly define the shape of gather response type

Author: nwaughachukwuma

src/web_search/search.py

@@ -29,7 +29,7 @@ def __init__(self, config: WebSearchConfig | None = None):
         # User-supplied plugins
         self.plugins = [p for p in self.config.plugins if isinstance(p, PluginSearch)]
 
-    def gather(self) -> Generator[BaseSearch]:
+    def gather(self) -> Generator[BaseSearch, None, None]:
         """
         Gather the relevant search tasks/logic and plugin
         """