update to new glfw key event function to fix compile error

As the new glfw-rs change the fn KeyEvent into WindowEvent::Key (https://github.com/bjz/glfw-rs/commit/60f8481e7dcaa4a8905013f06963e6bb794f89f0 && https://github.com/bjz/glfw-rs/commit/1c21628d628cbc3eccbea4c93bc8dc789ffb9b6d), need to update to fix compile error.