mlr3proba 0.7.1

• cleanup: removed all PipeOps and pipelines related to survival => regression reduction techniques (see #414)
• fix: $predict_type of survtoclassif_disctime and survtoclassif_IPCW was prob (classification type) and not crank (survival type)
• fix: G(t) is not filtered when t_max|p_max is specified in scoring rules (didn't influence evaluation at all)
• docs: Clarified the use and impact of using t_max in scoring rules, added examples in scoring rules and AUC scores
• feat: Added new argument remove_obs in scoring rules to remove observations with observed time t > t_max as a processing step to alleviate IPCW issues. This was before 'hard-coded' which made the Integrated Brier Score (msr("surv.graf")) differ minimally from other implementations and the original definition.