Make it clear this is testing an ftxui setting.

tests/ansi_parser.cpp

@@ -17,7 +17,7 @@ using namespace fmt;
 using namespace ftxui;
 
 std::string generate_colors() {
-  REQUIRE(ftxui::Terminal::ColorSupport() == Terminal::Color::TrueColor);
+  REQUIRE(ftxui::Terminal::ColorSupport() == ftxui::Terminal::Color::TrueColor);
 
   const int max_value = 255;
   const int value_increment = 8;