[ImgBot] Optimize images

*Total -- 3,345.03kb -> 2,896.83kb (13.4%)

/assets/img/il-1.jpg -- 222.42kb -> 172.28kb (22.54%)
/assets/img/yt-learn.png -- 1,496.56kb -> 1,290.09kb (13.8%)
/assets/img/yt-learn-a.png -- 1,342.81kb -> 1,162.52kb (13.43%)
/assets/img/Biology.jpg -- 64.96kb -> 58.15kb (10.48%)
/assets/img/yt-learn.jpg -- 81.50kb -> 78.59kb (3.57%)
/assets/img/Physics.jpg -- 59.37kb -> 58.47kb (1.51%)
/assets/img/Maths.jpg -- 77.40kb -> 76.72kb (0.88%)

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

Author: ImgBotApp