[ImgBot] Optimize images

*Total -- 1,261.69kb -> 1,109.57kb (12.06%)

/.github/screnshot.png -- 706.35kb -> 620.78kb (12.11%)
/screenshot.png -- 555.34kb -> 488.79kb (11.98%)

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

Author: ImgBotApp