[ImgBot] Optimize images

*Total -- 202.18kb -> 166.66kb (17.57%)

/docs/test-results/html/bg.png -- 186.46kb -> 151.57kb (18.71%)
/docs/test-results/html/favicon.svg -- 4.08kb -> 3.75kb (8.04%)
/docs/api/assets/icons.svg -- 11.64kb -> 11.34kb (2.57%)

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

Author: ImgBotApp