[ImgBot] Optimize images

*Total -- 293.48kb -> 242.63kb (17.32%)

/images/themes/29957ui.png -- 200.28kb -> 162.30kb (18.96%)
/images/themes/cyanmatrx.png -- 47.90kb -> 38.82kb (18.94%)
/images/themes/NightSky.jpeg -- 45.30kb -> 41.51kb (8.36%)

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

Author: ImgBotApp