[ImgBot] Optimize images

*Total -- 1,262.83kb -> 1,110.35kb (12.07%)

/.github/screnshot.png -- 707.49kb -> 621.56kb (12.15%)
/screenshot.png -- 555.34kb -> 488.79kb (11.98%)

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

Author: ImgBotApp