Address git clang review comment

Author: mcbarton

unittests/CppInterOp/InterpreterTest.cpp

@@ -23,6 +23,7 @@
 #include "gtest/gtest.h"
 
 #include <algorithm>
+#include <string>
 
 TEST(InterpreterTest, Version) {
   std::string version = Cpp::GetVersion();