[ImgBot] Optimize images

*Total -- 151.76kb -> 102.41kb (32.52%)

/assets/img/giphy-for-livechat-installed.png -- 68.56kb -> 46.10kb (32.76%)
/assets/img/giphy-for-livechat-uninstalled.png -- 67.45kb -> 45.63kb (32.35%)
/assets/img/giphy-for-livechat-message-box.png -- 15.75kb -> 10.68kb (32.17%)

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

Author: ImgBotApp