🐛 Fix std includes for GTest.h

Problem:
- GTest.h uses constructs from `std::` without including them; in later versions
  of GoogleTest they are not necessarily transitively included.

Solution:
- Add includes for:
  - `iomanip` (`std::left`, `std::setw`)
  - `iostream` (`std::cout`, `std::endl`)
  - `tuple` (`std::tie`)
  - `type_traits` (various e.g. `std::is_same`)

include/GUnit/GTest.h

@@ -10,8 +10,12 @@
 #include <gtest/gtest.h>
 
 #include <algorithm>
+#include <iomanip>
+#include <iostream>
 #include <memory>
 #include <string>
+#include <tuple>
+#include <type_traits>
 
 #include "GUnit/Detail/Preprocessor.h"
 #include "GUnit/Detail/RegexUtils.h"