[ImgBot] Optimize images

*Total -- 1,243.06kb -> 1,091.16kb (12.22%)

/.github/screnshot.png -- 687.72kb -> 602.38kb (12.41%)
/screenshot.png -- 555.34kb -> 488.79kb (11.98%)

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

Author: ImgBotApp