Fix stdlib build

typon/include/python/socket.hpp

@@ -80,14 +80,14 @@ struct socket__oo : referencemodel::moduletype<socket__oo<>> {
           co_await dot(self, close)();
           system_error(errno, "listen()");
         }
-        co_return {};
+        co_return None;
       }
     } static constexpr listen{};
 
     struct : referencemodel::method {
       typon::Task<typon::TyNone> operator()(auto self) const {
         co_await typon::io::close(self->fd);
-        co_return {};
+        co_return None;
       }
     } static constexpr close{};
 
@@ -107,7 +107,7 @@ struct socket__oo : referencemodel::moduletype<socket__oo<>> {
           co_await dot(self, close)();
           system_error(-sbytes, "send()");
         }
-        co_return {};
+        co_return None;
       }
     } static constexpr send{};