fix some warnings (#660)

Co-authored-by: ArthurSonzogni <sonzogniarthur@gmail.com>

examples/component/menu2.cpp

@@ -10,7 +10,7 @@
 #include "ftxui/component/screen_interactive.hpp"  // for Component, ScreenInteractive
 #include "ftxui/dom/elements.hpp"  // for text, separator, bold, hcenter, vbox, hbox, gauge, Element, operator|, border
 
-int main(int argc, const char* argv[]) {
+int main() {
   using namespace ftxui;
   auto screen = ScreenInteractive::TerminalOutput();