背景色変更では対応できなかった画像たち

[abebe0210]

• https://github.com/progedu/zen-algorithm-for-ml-assets/blob/main/08_%E6%B1%BA%E5%AE%9A%E6%9C%A8/img/pruning_alpha_change_effect.svg
• https://github.com/progedu/zen-algorithm-for-ml-assets/blob/main/08_%E6%B1%BA%E5%AE%9A%E6%9C%A8/img/pruning_alpha_equal_formula.svg
• https://github.com/progedu/zen-algorithm-for-ml-assets/blob/main/12_%E6%95%99%E5%B8%AB%E3%81%AA%E3%81%97%E5%AD%A6%E7%BF%92%E3%81%A8%E3%82%AF%E3%83%A9%E3%82%B9%E3%82%BF%E3%83%AA%E3%83%B3%E3%82%B0/img/dendrogram_cluster.svg