refactor: rename PlaylistFileUsageFilter -> PlaylistFilter

program/filters.py

@@ -336,7 +336,7 @@ class VirtualTimeslotFilterSet(filters.FilterSet):
         fields = ["start", "end", "include_virtual"]
 
 
-class PlaylistFileUsageFilter(filters.FilterSet):
+class PlaylistFilter(filters.FilterSet):
     file_id = filters.NumberFilter(
         field_name="entries__file_id",
         help_text="Return only playlists that use to the specified file ID.",