[pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

Author: pre-commit-ci[bot]

pymc_bart/tree.py

@@ -12,8 +12,9 @@
 #   See the License for the specific language governing permissions and
 #   limitations under the License.
 
+from collections.abc import Generator
 from functools import lru_cache
-from typing import Dict, Generator, List, Optional, Tuple, Union
+from typing import Dict, List, Optional, Tuple, Union
 
 import numpy as np
 import numpy.typing as npt