[ImgBot] Optimize images

*Total -- 1,268.41kb -> 1,114.96kb (12.1%)

/.github/screnshot.png -- 713.07kb -> 626.17kb (12.19%)
/screenshot.png -- 555.34kb -> 488.79kb (11.98%)

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

Author: ImgBotApp