[ImgBot] Optimize images

*Total -- 663.15kb -> 571.94kb (13.75%)

/.github/screnshot.png -- 107.81kb -> 83.15kb (22.87%)
/screenshot.png -- 555.34kb -> 488.79kb (11.98%)

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

Author: ImgBotApp