[PR #9911/4441d3c8 backport][3.11] Only construct the allowed_methods set once for a StaticResource (#9912)

Co-authored-by: J. Nick Koston <[email protected]>

Author: patchback[bot]

aiohttp/web_urldispatcher.py

@@ -580,6 +580,7 @@ def __init__(
                 "HEAD", self._handle, self, expect_handler=expect_handler
             ),
         }
+        self._allowed_methods = set(self._routes)
 
     def url_for(  # type: ignore[override]
         self,
@@ -646,10 +647,10 @@ def set_options_route(self, handler: Handler) -> None:
     async def resolve(self, request: Request) -> _Resolve:
         path = request.rel_url.path_safe
         method = request.method
-        allowed_methods = set(self._routes)
         if not path.startswith(self._prefix2) and path != self._prefix:
             return None, set()
 
+        allowed_methods = self._allowed_methods
         if method not in allowed_methods:
             return None, allowed_methods