Update __init__.py (#1213)

# BUGFIX: remove_fields_space() function will drop Feature object field

qlib/utils/__init__.py

@@ -518,7 +518,7 @@ def remove_fields_space(fields: [list, str, tuple]):
     """
     if isinstance(fields, str):
         return fields.replace(" ", "")
-    return [i.replace(" ", "") for i in fields if isinstance(i, str)]
+    return [i.replace(" ", "") if isinstance(i, str) else str(i) for i in fields]
 
 
 def normalize_cache_fields(fields: [list, tuple]):