[ImgBot] Optimize images

*Total -- 1,532.54kb -> 1,328.40kb (13.32%)

/Diagram.png -- 56.99kb -> 40.67kb (28.63%)
/plots/correlation_matrix_multi.png -- 103.65kb -> 74.95kb (27.69%)
/plots/correlation_matrix_bin.png -- 84.95kb -> 63.94kb (24.74%)
/plots/Pie_chart_binary.png -- 20.95kb -> 16.11kb (23.11%)
/plots/Pie_chart_multi.png -- 36.79kb -> 28.39kb (22.83%)
/plots/knn_real_pred_multi.png -- 68.89kb -> 54.68kb (20.63%)
/plots/lr_real_pred_multi.png -- 58.63kb -> 49.58kb (15.43%)
/plots/mlp_real_pred_bin.png -- 83.32kb -> 73.37kb (11.94%)
/plots/rf_real_pred_multi.png -- 81.52kb -> 72.94kb (10.53%)
/plots/lsvm_real_pred_multi.png -- 85.55kb -> 76.99kb (10%)
/plots/logr_real_pred_multi.png -- 86.42kb -> 77.89kb (9.87%)
/plots/mlp_real_pred_multi.png -- 87.88kb -> 79.67kb (9.35%)
/plots/lsvm_real_pred_bin.png -- 90.50kb -> 82.11kb (9.26%)
/plots/knn_real_pred_bin.png -- 90.34kb -> 82.06kb (9.16%)
/plots/lr_real_pred_bin.png -- 91.42kb -> 83.08kb (9.12%)
/plots/logr_real_pred_bin.png -- 91.12kb -> 82.87kb (9.06%)
/plots/dt_real_pred_bin.png -- 107.84kb -> 99.03kb (8.17%)
/plots/dt_real_pred_multi.png -- 101.37kb -> 93.24kb (8.02%)
/plots/rf_real_pred_bin.png -- 104.42kb -> 96.83kb (7.26%)

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

Author: ImgBotApp