[ImgBot] Optimize images

*Total -- 299.17kb -> 238.54kb (20.26%)

/src/static/images/dashboard.png -- 134.87kb -> 103.59kb (23.2%)
/src/static/images/memory.png -- 44.13kb -> 34.43kb (22%)
/src/static/images/disk.png -- 46.41kb -> 36.73kb (20.85%)
/src/static/images/speedtest.png -- 37.02kb -> 30.99kb (16.3%)
/src/static/images/cpu.png -- 36.73kb -> 32.81kb (10.68%)

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

Author: ImgBotApp