Bugfix/188 some tests failing when running locally in python 313 environment

[sdahdah]

Resolves #188

Proposed Changes

• Update estimators to pass new scikit-learn estimator checks
• Pin range of scikit-learn versions
• Add Python 3.13 to CI

Checklist

• Write unit tests
• Add new estimators to existing scikit-learn compatibility tests
• Write examples in docstrings
• Update Sphinx documentation
• Bump version number and date in setup.py, CITATION.cff, and
  README.rst

[matt-graham]

Thanks - confirming this resolves #188 for me locally and from a quick look through diff all changes look sensible to me.