Homepage: use https (flutter#4)

Author: kevmoo

pubspec.yaml

@@ -1,7 +1,7 @@
 name: http_multi_server
 version: 2.0.4-dev
 author: "Dart Team <[email protected]>"
-homepage: http://github.com/dart-lang/http_multi_server
+homepage: https://github.com/dart-lang/http_multi_server
 description:
   A dart:io HttpServer wrapper that handles requests from multiple servers.
 environment: