change base_estimator to estimator

[jckkvs]

ref. https://scikit-learn.org/stable/modules/generated/sklearn.linear_model.RANSACRegressor.html In sklearn, base_estimator was deprecated.

[jckkvs]

Hello, @cerlymarco

In this pull request, I have made changes to ensure compatibility with the latest version of scikit-learn.

Changes Made

1. Modified occurrences of base_estimator to estimator.
2. Replaced max_features="auto" with max_features=1.0.

[jckkvs]

@cerlymarco
Hello, what do you think about this pull request?

[victoraalves]

@cerlymarco Let me first acknowledge you for developing the linear-tree package. It is incredibly useful. Second, I'd like to report that I am facing the same issue that @jckkvs is reporting. Now in sklearn=1.7.0 the deprecation warning is extinct and the base_estimator is actually nonexistent, which unfortunately breaks linear-tree. Are there any plans to merge this into the main branch? I am more than happy to participate in reviewing this PR. Thanks!