fix: Import Self from typing_extensions

pyproject.toml

@@ -23,6 +23,7 @@ classifiers = [
 requires-python = ">=3.8"
 dependencies = [
     "bidsschematools >=0.11",
+    "typing_extensions",
     "attrs",
     "httpx",
 ]

src/bids_validator/types/files.py

@@ -5,9 +5,10 @@
 import stat
 from functools import cached_property
 from pathlib import Path
-from typing import Dict, Self, Union
+from typing import Dict, Union
 
 import attrs
+from typing_extensions import Self  # PY310
 
 __all__ = ('FileTree',)