Fix Projects::MergeRequestsController#show spec

Signed-off-by: Rémy Coutable <remy@rymai.me>

spec/controllers/projects/merge_requests_controller_spec.rb

@@ -290,7 +290,7 @@ describe Projects::MergeRequestsController do
 
           recorded = ActiveRecord::QueryRecorder.new { go(format: :json) }
 
-          expect(recorded.count).to be_within(1).of(100)
+          expect(recorded.count).to be_within(3).of(100)
           expect(recorded.cached_count).to eq(0)
         end
       end