[ImgBot] Optimize images

*Total -- 2,072.54kb -> 1,869.02kb (9.82%)

/assets/logo.png -- 176.17kb -> 56.66kb (67.84%)
/assets/settings.png -- 104.81kb -> 57.93kb (44.73%)
/assets/demo.gif -- 1,791.56kb -> 1,754.44kb (2.07%)

Signed-off-by: ImgBotApp <ImgBotHelp@gmail.com>

Author: ImgBotApp