[ImgBot] Optimize images (abess-team#109)

* [ImgBot] Optimize images

*Total -- 3,396.34kb -> 2,971.23kb (12.52%)

/docs/source/contribute/figure/architecture-scope.png -- 270.63kb -> 86.37kb (68.09%)
/docs/source/_static/404.png -- 28.87kb -> 11.29kb (60.88%)
/docs/source/gallery/SurvivalModels/Figure/competing_risk_model.png -- 24.39kb -> 12.44kb (48.98%)
/docs/source/gallery/SurvivalModels/Figure/tradition_survival.png -- 14.75kb -> 7.82kb (47%)
/docs/source/userguide/figure/tf.png -- 113.07kb -> 71.77kb (36.52%)
/docs/source/gallery/image/ic.png -- 66.87kb -> 47.30kb (29.26%)
/docs/source/gallery/image/linear.png -- 31.27kb -> 22.28kb (28.75%)
/docs/source/gallery/image/survival.png -- 17.22kb -> 12.60kb (26.82%)
/docs/source/userguide/figure/variable_selection.png -- 49.35kb -> 36.79kb (25.46%)
/docs/source/gallery/image/graph.png -- 10.31kb -> 7.71kb (25.23%)
/docs/source/gallery/image/mis.png -- 10.16kb -> 7.87kb (22.52%)
/docs/source/userguide/figure/nonlinear_variable_selection.png -- 24.80kb -> 19.81kb (20.13%)
/docs/source/userguide/figure/portfolio_selection.png -- 82.00kb -> 66.63kb (18.74%)
/docs/source/userguide/figure/precision_matrix.png -- 23.98kb -> 19.59kb (18.3%)
/docs/source/_static/skscope.png -- 61.24kb -> 50.58kb (17.4%)
/docs/source/_static/skscope-light.png -- 62.76kb -> 51.99kb (17.16%)
/docs/source/_static/skscope-dark.png -- 64.19kb -> 53.85kb (16.1%)
/docs/source/userguide/figure/trend_filter.png -- 142.50kb -> 125.59kb (11.87%)
/docs/source/gallery/image/filtering.png -- 43.20kb -> 38.29kb (11.35%)
/docs/source/first_page.png -- 2,153.35kb -> 2,119.22kb (1.59%)
/docs/source/_static/skscope-light.svg -- 39.30kb -> 39.29kb (0.03%)
/docs/source/_static/skscope-dark.svg -- 62.15kb -> 62.14kb (0.02%)

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

* Auto code format (abess-team#110)

Co-authored-by: imgbot[bot] <imgbot[bot]@users.noreply.github.com>

---------

Signed-off-by: ImgBotApp <[email protected]>
Co-authored-by: ImgBotApp <[email protected]>
Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
Co-authored-by: imgbot[bot] <imgbot[bot]@users.noreply.github.com>