Add topics to pubspec.yaml (#1199)

Author: jonasfj

pkgs/http/pubspec.yaml

@@ -2,6 +2,9 @@ name: http
 version: 1.2.2-wip
 description: A composable, multi-platform, Future-based API for HTTP requests.
 repository: https://github.com/dart-lang/http/tree/master/pkgs/http
+topics:
+ - http
+ - network
 
 environment:
   sdk: ^3.3.0