[BUG] Fixes for scikit-learn v1.4

[naoise-h]

This PR provides a number of bugfixes for the newly-released Scikit-learn v1.4. Explicit support for Python 3.12 is also added.

• Minor changes to DecisionTreeClassifier and _logistic_regression_path

[codecov]

Codecov Report

Attention: 2 lines in your changes are missing coverage. Please review.

Comparison is base (0e6cea9) 99.16% compared to head (3d9f1cf) 99.09%.

Files	Patch %	Lines
diffprivlib/models/forest.py	80.00%	1 Missing ⚠️
diffprivlib/models/logistic_regression.py	83.33%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #91      +/-   ##
==========================================
- Coverage   99.16%   99.09%   -0.08%     
==========================================
  Files          34       34              
  Lines        2645     2653       +8     
==========================================
+ Hits         2623     2629       +6     
- Misses         22       24       +2     

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