Improve code readability in s3fs _prune_deleted_files function

Use .values() instead of .keys() for better Pythonic code style.
This addresses the review comment from bdrx312.

Signed-off-by: GRomR1 <[email protected]>

Author: GRomR1

salt/fileserver/s3fs.py

@@ -591,8 +591,8 @@ def _prune_deleted_files(metadata):
                     roots.add(root)
 
             for meta in env_data:
-                for bucket in meta.keys():
-                    for obj in meta[bucket]:
+                for objects in meta.values():
+                    for obj in objects:
                         cached_files.add(obj["Key"])
 
     if log.isEnabledFor(logging.DEBUG):