Depend on typing-extensions for Python<3.11; avoid it otherwise

pyproject.toml

@@ -26,6 +26,9 @@ classifiers = [
     "Programming Language :: Python :: 3.13",
     "Topic :: Software Development :: Libraries",
 ]
+dependencies = [
+    "typing-extensions; python_version < '3.11'",
+]
 
 [project.urls]
 Homepage = "https://github.com/mdomke/python-ulid"

ulid/__init__.py

@@ -13,19 +13,23 @@
 from typing import TYPE_CHECKING
 from typing import TypeVar
 
-from typing_extensions import Self
-
 from ulid import base32
 from ulid import constants
 
 
 if TYPE_CHECKING:  # pragma: no cover
+    import sys
     from collections.abc import Callable
 
     from pydantic import GetCoreSchemaHandler
     from pydantic import ValidatorFunctionWrapHandler
     from pydantic_core import CoreSchema
 
+    if sys.version_info >= (3, 11):
+        from typing import Self
+    else:
+        from typing_extensions import Self
+
 try:
     from importlib.metadata import version
 except ImportError:  # pragma: no cover
@@ -199,7 +203,7 @@ def parse(cls, value: Any) -> Self:
             a value when they're unsure what format/primitive type it will be given in.
         """
         if isinstance(value, ULID):
-            return cast(Self, value)
+            return cast("Self", value)
         if isinstance(value, uuid.UUID):
             return cls.from_uuid(value)
         if isinstance(value, str):