fix some LGTM issues

src/maggma/cli/source_loader.py

@@ -1,20 +1,19 @@
 import importlib.util
 import sys
-import types
 from glob import glob
 from importlib.abc import Loader, MetaPathFinder
 from importlib.machinery import ModuleSpec, SourceFileLoader
 from pathlib import Path
 from typing import List
-from nbformat import read
-from regex import match
+
 
 from maggma.core import Builder
 
 try:
     import nbformat
     from IPython import get_ipython
     from IPython.core.interactiveshell import InteractiveShell
+    from regex import match
 except ModuleNotFoundError:
     pass
 

src/maggma/stores/gridfs.py

@@ -10,7 +10,7 @@
 import json
 import zlib
 from datetime import datetime
-from typing import Any, Dict, Iterator, List, Optional, Set, Tuple, Union
+from typing import Any, Dict, Iterator, List, Optional, Tuple, Union
 
 import gridfs
 from monty.dev import deprecated