use quotes for local headers

Signed-off-by: Patrick Venture <venture@google.com>
Change-Id: I95f247bd17cffab8b9ef3337f48336f8d7059c2d
diff --git a/include/Thresholds.hpp b/include/Thresholds.hpp
index 37ce108..f1e7cc6 100644
--- a/include/Thresholds.hpp
+++ b/include/Thresholds.hpp
@@ -1,5 +1,6 @@
 #pragma once
-#include <Utils.hpp>
+#include "Utils.hpp"
+
 #include <boost/asio/io_service.hpp>
 #include <nlohmann/json.hpp>