chore: remove python<3.8 compatibility code

lektor/imagetools/image_info.py

@@ -11,6 +11,7 @@
 from contextlib import suppress
 from pathlib import Path
 from typing import BinaryIO
+from typing import Final
 from typing import Generator
 from typing import Mapping
 from typing import NamedTuple
@@ -27,10 +28,6 @@
     from typing import Literal
     from _typeshed import SupportsRead
 
-if sys.version_info >= (3, 8):
-    from typing import Final
-else:
-    from typing_extensions import Final
 
 if sys.version_info >= (3, 10):
     from typing import TypeAlias

lektor/imagetools/thumbnail.py

@@ -5,12 +5,12 @@
 import io
 import math
 import posixpath
-import sys
 from enum import Enum
 from functools import partial
 from pathlib import Path
 from typing import Any
 from typing import ClassVar
+from typing import Final
 from typing import Iterable
 from typing import Iterator
 from typing import Mapping
@@ -35,11 +35,6 @@
     from lektor.builder import Artifact
     from lektor.context import Context
 
-if sys.version_info >= (3, 8):
-    from typing import Final
-else:
-    from typing_extensions import Final
-
 
 class ThumbnailMode(Enum):
     FIT = "fit"