Malformed logger call in ButinaSplitter.split raises string-formatting error

Description

ButinaSplitter.split logs the clustering cutoff with a malformed logger call:

https://github.com/deepchem/deepchem/blob/master/deepchem/splits/splitters.py#L1238

logger.info("Performing butina clustering with cutoff of", self.cutoff)

The format string has no % placeholder, yet a second positional argument (self.cutoff) is passed. The logging module defers interpolation and treats trailing positional arguments as %-style format args. When the record is emitted it raises TypeError: not all arguments converted during string formatting, which the logging framework routes to handleError and prints as a traceback on stderr. The cutoff value the message was meant to show is never logged.

Steps to reproduce

Run any Butina split with logging at INFO level:

import logging
logging.basicConfig(level=logging.INFO)
import numpy as np
import deepchem as dc

smiles = ['C', 'CC', 'CCC', 'CCCC', 'CCCCC']
ds = dc.data.DiskDataset.from_numpy(X=np.zeros(len(smiles)), ids=smiles)
dc.splits.ButinaSplitter().train_test_split(ds)

A --- Logging error --- traceback with TypeError: not all arguments converted during string formatting is printed to stderr.

Expected

The cutoff value is interpolated and logged without error.