[ImgBot] Optimize images

*Total -- 646.57kb -> 554.66kb (14.21%)

/public/assets/images/background/sliderbg.jpg -- 33.75kb -> 16.72kb (50.47%)
/.github/screnshot.png -- 57.48kb -> 49.16kb (14.47%)
/screenshot.png -- 555.34kb -> 488.79kb (11.98%)

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

Author: ImgBotApp