Fix get_metadata return annotation and import order in misctypes

get_metadata() always returns a dict, never None.  The imports in
RemoteReadableAsset.open() were not sorted as the pinned isort (5.12.0)
of the pre-commit hook expects, so any change to dandi/misctypes.py
re-sorted them.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Qn5WBSiQgoZoL4fytF6nEr

Author: claude

dandi/metadata/nwb.py

@@ -31,7 +31,7 @@
 @metadata_cache.memoize_path
 def get_metadata(
     path: str | Path | Readable, digest: Digest | None = None
-) -> dict | None:
+) -> dict[str, Any]:
     """
     Get "flatdata" from a .nwb file
 

dandi/misctypes.py

@@ -343,9 +343,8 @@ class RemoteReadableAsset(Readable):
 
     def open(self) -> IO[bytes]:
         # Optional dependency:
-        import fsspec
-
         from aiohttp import ClientTimeout
+        import fsspec
 
         # We need to call open() on the return value of fsspec.open() because
         # otherwise the filehandle will only be opened when used to enter a