[ImgBot] Optimize images

*Total -- 1,745.41kb -> 1,624.01kb (6.96%)

/assets/icon_128x128.png -- 12.33kb -> 11.02kb (10.67%)
/assets/icon_256x256.png -- 52.76kb -> 47.92kb (9.19%)
/assets/deepdip_logo.png -- 1,419.54kb -> 1,321.96kb (6.87%)
/assets/icon_512x512.png -- 257.25kb -> 239.83kb (6.77%)
/assets/icon_64x64.png -- 3.52kb -> 3.29kb (6.63%)

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

Author: ImgBotApp