Don't add state query param twice

Author: passsy

lib/src/common/pulls_service.dart

@@ -32,7 +32,7 @@ class PullRequestsService extends Service {
 
     return PaginationHelper(github).objects(
         'GET',
-        '/repos/${slug.fullName}/pulls?state=$state',
+        '/repos/${slug.fullName}/pulls',
         (dynamic i) => PullRequest.fromJson(i),
         pages: pages,
         params: params);