[ImgBot] Optimize images

*Total -- 1,434.08kb -> 1,376.51kb (4.01%)

/static/icons/writer.png -- 18.10kb -> 15.09kb (16.64%)
/static/img/tutorials/ml/git-dvc.jpg -- 138.41kb -> 131.74kb (4.82%)
/static/img/tutorials/ml/git-dvc-s3.png -- 1,117.10kb -> 1,074.39kb (3.82%)
/static/img/tutorials/ml/max-pooling-vs-average-pooling.jpg -- 160.48kb -> 155.29kb (3.23%)

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

Author: ImgBotApp