support for "huber" objective in the LGBM Booster

[LukaszCmielowski]

Support for Booster with objectives other than "regression".

RuntimeError: LightGBM objective should be cleaned already not 'huber'.

pytest updated accordingly.

[LukaszCmielowski]

@xadupre please take a look. Thx.

[xadupre]

It looks ok to me. You should sign your commits (git commit -s ...) to avoid the DCO issue. You can black . as well to fix the style issues then ruff check . to detect them.

[LukaszCmielowski]

Black & Ruff updated. Working on DCO ...

[LukaszCmielowski]

@xadupre DCO fixed.

[LukaszCmielowski]

@xadupre I see some checks (unrelated to this PR) failing due to xgb env issue:

XGBoost Library (libxgboost.dylib) could not be loaded

Let me know what are the next steps. Thanks.

[xadupre]

@xadupre I see some checks (unrelated to this PR) failing due to xgb env issue:

XGBoost Library (libxgboost.dylib) could not be loaded

Let me know what are the next steps. Thanks.

I fix CI. You need to update your branch to unlock you.

[LukaszCmielowski]

@xadupre done.