http_utility_test: fix headers

"gmock/gmock.h" should be replaced with "gtest/gtest.h" given that only
GTest macors are used.

"http_utility.hpp" is a local header and "gtest/gtest.h" is a header in
dependencies. The convention is to use <> for dependency headers.

Reference: https://gcc.gnu.org/onlinedocs/cpp/Search-Path.html

Tested: unit test passed

Signed-off-by: Nan Zhou <nanzhoumails@gmail.com>
Change-Id: I42b077090df59ee1c4fbfab3199d2ee9b4b242dc
diff --git a/include/ut/http_utility_test.cpp b/include/ut/http_utility_test.cpp
index 32591a4..5fddc57 100644
--- a/include/ut/http_utility_test.cpp
+++ b/include/ut/http_utility_test.cpp
@@ -1,6 +1,6 @@
-#include <http_utility.hpp>
+#include "http_utility.hpp"
 
-#include "gmock/gmock.h"
+#include <gtest/gtest.h>
 
 TEST(HttpUtility, requestPrefersHtml)
 {