Fix unimplemented default TypeVar argument in 3.13a4

Author: JonathanPlasse

hypothesis-python/src/hypothesis/strategies/_internal/strategies.py

@@ -52,7 +52,8 @@
 from hypothesis.strategies._internal.utils import defines_strategy
 from hypothesis.utils.conventions import UniqueIdentifier
 
-if sys.version_info >= (3, 13):
+# TODO: Use `(3, 13)` once Python 3.13 is released.
+if sys.version_info >= (3, 13, 0, "final"):
     Ex = TypeVar("Ex", covariant=True, default=Any)
 elif TYPE_CHECKING:
     from typing_extensions import TypeVar  # type: ignore[assignment]