Update CMakeLists.txt

Deleted media/.gitkeep, media/dog.png, media/sheep.png, media/sheep2.png, media/shepherd.png, media/wolf.png, media/wolfne1.png, media/wolfne2.png, media/wolfne3.png, media/wolfnw1.png, media/wolfnw2.png, media/wolfnw3.png, media/wolfse1.png, media/wolfse2.png, media/wolfse3.png, media/wolfsw1.png, media/wolfsw2.png, media/wolfsw3.png, héritage multiple/.gitkeep, héritage multiple/Project_SDL1.cpp, héritage multiple/Project_SDL1.h, Project_SDL1.cpp, Project_SDL1.h, main.cpp