Fix type string in Tilesets.

This value is a constant and will always be "tileset". No need to load it from the file.

Author: Cleptomania

pytiled_parser/tileset.py

@@ -130,11 +130,11 @@ class Tileset:
     tile_count: int
     columns: int
 
+    type: str = "tileset"
+
     spacing: int = 0
     margin: int = 0
 
-    type: Optional[str] = None
-
     tiled_version: Optional[str] = None
     version: Optional[str] = None
 
@@ -350,9 +350,6 @@ def cast(raw_tileset: RawTileSet, external_path: Optional[Path] = None) -> Tiles
         margin=raw_tileset["margin"],
     )
 
-    if raw_tileset.get("type") is not None:
-        tileset.type = raw_tileset["type"]
-
     if raw_tileset.get("version") is not None:
         if isinstance(raw_tileset["version"], float):
             tileset.version = str(raw_tileset["version"])