Remove workaround for python<3.8 to silence pylint.

TF-GNN has required python>=3.8 since r0.5 from January 2023.

PiperOrigin-RevId: 666839656

tensorflow_gnn/runner/interfaces.py

@@ -17,21 +17,11 @@
 
 import abc
 import dataclasses
-import sys
-from typing import Callable, Mapping, Optional, Sequence, TypeVar, Union
+from typing import Callable, Mapping, Optional, Sequence, TypeVar, Union, Protocol, runtime_checkable
 
 import tensorflow as tf
 import tensorflow_gnn as tfgnn
 
-# pylint:disable=g-import-not-at-top
-if sys.version_info >= (3, 8):
-  from typing import Protocol
-  from typing import runtime_checkable
-else:
-  from typing_extensions import Protocol
-  from typing_extensions import runtime_checkable
-# pylint:enable=g-import-not-at-top
-
 T = TypeVar("T")
 OneOrMappingOf = Union[T, Mapping[str, T]]
 OneOrSequenceOf = Union[T, Sequence[T]]