Fix linting. (#5089)

* Fix linting.

* Cruft.

src/toil/lib/aws/s3.py

@@ -13,13 +13,16 @@
 # limitations under the License.
 import logging
 from typing import List
+
+from mypy_boto3_s3.type_defs import ListMultipartUploadsOutputTypeDef
+
 from toil.lib.aws import session, AWSServerErrors
 from toil.lib.retry import retry
 
 logger = logging.getLogger(__name__)
 
 
 @retry(errors=[AWSServerErrors])
-def list_multipart_uploads(bucket: str, region: str, prefix: str, max_uploads: int = 1) -> List[str]:
+def list_multipart_uploads(bucket: str, region: str, prefix: str, max_uploads: int = 1) -> ListMultipartUploadsOutputTypeDef:
     s3_client = session.client("s3", region_name=region)
     return s3_client.list_multipart_uploads(Bucket=bucket, MaxUploads=max_uploads, Prefix=prefix)