[ImgBot] Optimize images

*Total -- 280.86kb -> 238.42kb (15.11%)

/icon.png -- 25.39kb -> 19.59kb (22.85%)
/icon-512.png -- 93.42kb -> 79.36kb (15.05%)
/icon-512-maskable.png -- 92.53kb -> 78.76kb (14.88%)
/apple-touch-icon.png -- 21.44kb -> 18.68kb (12.89%)
/icon-192.png -- 24.03kb -> 21.01kb (12.58%)
/icon-192-maskable.png -- 24.03kb -> 21.01kb (12.58%)

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

Author: ImgBotApp