[ImgBot] Optimize images

*Total -- 231.26kb -> 216.14kb (6.54%)

/example/web/icons/Icon-maskable-512.png -- 20.51kb -> 10.54kb (48.61%)
/example/web/icons/Icon-maskable-192.png -- 5.46kb -> 3.66kb (33.05%)
/display/flicker.gif -- 205.29kb -> 201.95kb (1.63%)

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

Author: ImgBotApp