chore(tileset): Removed FIXME for completed task

pytiled_parser/tileset.py

@@ -190,8 +190,6 @@ class RawTerrain(TypedDict):
 class RawTile(TypedDict):
     """ The keys and their types that appear in a Tile JSON Object."""
 
-    # FIXME: Implement objectgroup, can't be done until TileLayer's are implemented
-
     animation: List[RawFrame]
     id: int
     image: str