Update to Python 3.14.0b2 (#14182)

stdlib/string/templatelib.pyi

@@ -1,4 +1,5 @@
 from collections.abc import Iterator
+from types import GenericAlias
 from typing import Any, Literal, final
 
 __all__ = ["Interpolation", "Template"]
@@ -11,6 +12,7 @@ class Template:  # TODO: consider making `Template` generic on `TypeVarTuple`
     def __new__(cls, *args: str | Interpolation) -> Template: ...
     def __iter__(self) -> Iterator[str | Interpolation]: ...
     def __add__(self, other: Template | str) -> Template: ...
+    def __class_getitem__(cls, item: Any, /) -> GenericAlias: ...
     @property
     def values(self) -> tuple[Any, ...]: ...  # Tuple of interpolation values, which can have any type
 
@@ -26,3 +28,4 @@ class Interpolation:
     def __new__(
         cls, value: Any, expression: str, conversion: Literal["a", "r", "s"] | None = None, format_spec: str = ""
     ) -> Interpolation: ...
+    def __class_getitem__(cls, item: Any, /) -> GenericAlias: ...