[ImgBot] Optimize images

*Total -- 268.91kb -> 169.04kb (37.14%)

/resources/dmg_background.png -- 8.33kb -> 1.39kb (83.33%)
/resources/kolosal.iconset/icon_512x512.png -- 90.37kb -> 55.29kb (38.82%)
/resources/kolosal.iconset/icon_256x256@2x.png -- 90.05kb -> 55.21kb (38.69%)
/resources/kolosal.iconset/icon_128x128@2x.png -- 31.80kb -> 21.84kb (31.32%)
/resources/kolosal.iconset/icon_256x256.png -- 31.77kb -> 21.99kb (30.8%)
/resources/kolosal.iconset/icon_128x128.png -- 12.10kb -> 9.41kb (22.28%)
/resources/kolosal.iconset/icon_32x32@2x.png -- 4.48kb -> 3.91kb (12.8%)

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

Author: ImgBotApp