[ImgBot] Optimize images

*Total -- 90.60kb -> 42.39kb (53.22%)

/assets/logo.png -- 46.55kb -> 20.55kb (55.86%)
/assets/logo-w.png -- 42.62kb -> 20.46kb (51.99%)
/assets/favicon.png -- 1.43kb -> 1.38kb (3.82%)

Signed-off-by: ImgBotApp <[email protected]>

Author: ImgBotApp