[ImgBot] Optimize images

*Total -- 173.11kb -> 139.45kb (19.44%)

/littlelink/icons/f-droid.svg -- 22.75kb -> 17.54kb (22.91%)
/littlelink/icons/openstreetmap.svg -- 150.36kb -> 121.92kb (18.92%)

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

Author: ImgBotApp