Fix the warnings

[Thomas1995]

In file included from bot.cpp:5:0:
bot.cpp: In member function ‘Minigame Bot::ChooseMinigame()’:
../util/debug.h:6:58: warning: format ‘%d’ expects argument of type ‘int’, but argument 3 has type ‘std::vector<Minigame>::size_type {aka long unsigned int}’ [-Wformat=]
 #define debug(...) if(DEBUG) {fprintf(stderr, __VA_ARGS__);}
                                                          ^
bot.cpp:55:2: note: in expansion of macro ‘debug’
  debug("I have %d games available\n", games.size());
  ^
../util/debug.h:6:58: warning: format ‘%d’ expects argument of type ‘int’, but argument 3 has type ‘std::vector<Minigame>::size_type {aka long unsigned int}’ [-Wformat=]
 #define debug(...) if(DEBUG) {fprintf(stderr, __VA_ARGS__);}
                                                          ^
bot.cpp:62:2: note: in expansion of macro ‘debug’
  debug("I now have %d games available\n", games.size());
  ^

[Thomas1995]

Fixed in c732532.