[BUG] From scikit-learn 1.7, `__sklearn_tags__` needs to be defined.

[jamblejoe]

Describe the bug

Instead of and scikit-learn enforces to define the `` method, as suggested by the following FutureWarning:

The RandomUnderSampler or classes from which it inherits use `_get_tags` and `_more_tags`. Please define the `__sklearn_tags__` method, or inherit from `sklearn.base.BaseEstimator` and/or other appropriate mixins such as `sklearn.base.TransformerMixin`, `sklearn.base.ClassifierMixin`, `sklearn.base.RegressorMixin`, and `sklearn.base.OutlierMixin`. From scikit-learn 1.7, not defining `__sklearn_tags__` will raise an error.

Steps/Code to Reproduce

from imblearn.under_sampling import RandomUnderSampler

RandomUnderSampler()

Expected Results

No warning is shown.

Actual Results

.../lib/python3.10/site-packages/sklearn/utils/_tags.py:354: FutureWarning: The RandomUnderSampler or classes from which it inherits use `_get_tags` and `_more_tags`. Please define the `__sklearn_tags__` method, or inherit from `sklearn.base.BaseEstimator` and/or other appropriate mixins such as `sklearn.base.TransformerMixin`, `sklearn.base.ClassifierMixin`, `sklearn.base.RegressorMixin`, and `sklearn.base.OutlierMixin`. From scikit-learn 1.7, not defining `__sklearn_tags__` will raise an error.
  warnings.warn(

Versions

System:
    python: 3.10.16 | packaged by conda-forge | (main, Dec  5 2024, 14:16:10) [GCC 13.3.0]
executable: /opt/conda/envs/.../bin/python
   machine: Linux-4.18.0-553.16.1.el8_10.x86_64-x86_64-with-glibc2.35

Python dependencies:
      sklearn: 1.6.0
          pip: 24.3.1
   setuptools: 75.6.0
        numpy: 2.2.0
        scipy: 1.14.1
       Cython: None
       pandas: 2.2.3
   matplotlib: 3.10.0
       joblib: 1.4.2
threadpoolctl: 3.5.0

Built with OpenMP: True

threadpoolctl info:
       user_api: blas
   internal_api: openblas
    num_threads: 64
         prefix: libopenblas
       filepath: /opt/conda/envs/.../lib/libopenblasp-r0.3.28.so
        version: 0.3.28
threading_layer: pthreads
   architecture: SapphireRapids

       user_api: openmp
   internal_api: openmp
    num_threads: 64
         prefix: libgomp
       filepath: /opt/conda/envs/.../lib/libgomp.so.1.0.0
        version: None

[glemaitre]

Already merged in main. I'm going to make a release soonish.