[ImgBot] Optimize images

*Total -- 627.30kb -> 552.51kb (11.92%)

/image/runtime.png -- 173.94kb -> 123.58kb (28.95%)
/image/high_dimension_result_2.png -- 159.89kb -> 142.39kb (10.94%)
/image/high_dimension_result_1.png -- 293.48kb -> 286.54kb (2.36%)

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

Author: ImgBotApp