chore: improve rbi typedef for page classes (#154)

Author: stainless-app[bot]

rbi/lib/orb/page.rbi

@@ -29,9 +29,9 @@ module Orb
         headers: T.any(T::Hash[String, String], Net::HTTPHeader),
         page_data: T::Hash[Symbol, T.anything]
       )
-        .void
+        .returns(T.attached_class)
     end
-    def initialize(client:, req:, headers:, page_data:)
+    def self.new(client:, req:, headers:, page_data:)
     end
 
     class PaginationMetadata < Orb::BaseModel