[ImgBot] Optimize images (#644)

*Total -- 1,253.27kb -> 774.20kb (38.23%)

/Dashboard.png -- 1,072.21kb -> 617.66kb (42.39%)
/ProxyPy.png -- 56.83kb -> 38.15kb (32.86%)
/shortlink.gif -- 124.23kb -> 118.39kb (4.7%)

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

Co-authored-by: ImgBotApp <[email protected]>

Author: imgbot[bot]