[ImgBot] Optimize images (#128)

*Total -- 544.01kb -> 412.04kb (24.26%)

/.github/images/prs-screenshot-tab-stats.png -- 26.76kb -> 18.34kb (31.47%)
/.github/images/prs-screenshot-tell.png -- 19.28kb -> 13.45kb (30.25%)
/.github/images/prs-screenshot-01.png -- 316.26kb -> 232.81kb (26.39%)
/.github/images/prs-screenshot-unlocked.png -- 161.24kb -> 129.17kb (19.89%)
/.github/images/prs-logo.png -- 20.47kb -> 18.27kb (10.73%)

Signed-off-by: ImgBotApp <[email protected]>
Co-authored-by: ImgBotApp <[email protected]>

Author: imgbot[bot]