Remove type checking guards

Author: dstansby

numcodecs/checksum32.py

@@ -1,17 +1,15 @@
 import struct
 import zlib
 from collections.abc import Callable
-from typing import TYPE_CHECKING, Optional
+from typing import Optional
 
 import numpy as np
+from typing_extensions import Buffer
 
 from .abc import Codec
 from .compat import ensure_contiguous_ndarray, ndarray_copy
 from .jenkins import jenkins_lookup3
 
-if TYPE_CHECKING:
-    from typing_extensions import Buffer
-
 
 class Checksum32(Codec):
     # override in sub-class

numcodecs/registry.py

@@ -2,14 +2,10 @@
 applications to dynamically register and look-up codec classes."""
 
 import logging
-from importlib.metadata import entry_points
-from typing import TYPE_CHECKING
+from importlib.metadata import EntryPoints, entry_points
 
 from numcodecs.abc import Codec
 
-if TYPE_CHECKING:
-    from importlib.metadata import EntryPoints
-
 logger = logging.getLogger("numcodecs")
 codec_registry: dict[str, Codec] = {}
 entries: dict[str, "EntryPoints"] = {}