1.9.0
MNT remove tree DOUBLE and DTYPE (#33948)
MNT Switch to absolute imports enforced by `ruff` (#31847)
FEA Add support for missing values in tree estimators with `criterion="absolute_error"` by greatly simplifying the logic (#32119)
FIX: Use intro sort for `simultaneous_sort` (2 way partitioning) (#33252)
Fix color conversion to rgb hexstring (#33845)
MNT move sorting functions from `tree/` to `utils/_sorting.pyx` (#33979)
MNT Enforce ruff rules (RUF) (#30694)
MNT cleanup Cython imports in tree module (#33947)
TST: Decision trees: add test for split optimality (#32193)
BLD Reduce generated build file path lengths to avoid Windows path length limitation (#31212)