[ImgBot] Optimize images

*Total -- 706.57kb -> 604.18kb (14.49%)

/.github/screnshot.png -- 151.23kb -> 115.39kb (23.7%)
/screenshot.png -- 555.34kb -> 488.79kb (11.98%)

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

Author: ImgBotApp