py: use Buffer instead of ByteString on Python 3.12+

`ByteString` was
[deprecated](https://docs.python.org/3.12/whatsnew/3.12.html#deprecated)
in Python 3.12 and
[removed](https://docs.python.org/3.14/whatsnew/3.14.html#collections-abc) in
3.14.

`collections.abc.Buffer` is available since Python 3.12.

Fixes #238.
Closes #262.

Author: rathann

docs/news.rst

@@ -59,6 +59,8 @@ Changes
   and we didn't run tests on this platform.
 * We now use `Py_REFCNT(obj)` instead of accessing `(*obj)->ob_refcnt` directly.
   This fixes a nogil / multi-threaded compile error. (#201)
+* We now `collections.abs.Buffer` on Python 3.12+ instead of `typing.ByteString`,
+  as `typing.ByteString` was deprecated and later removed. (#238, #262)
 
 Backwards Compatibility Notes
 -----------------------------

zstandard/__init__.py

@@ -18,7 +18,12 @@
 import io
 import os
 import platform
-from typing import ByteString
+import sys
+
+if sys.version_info >= (3, 12):
+    from collections.abc import Buffer
+else:
+    from typing import ByteString as Buffer
 
 # Some Python implementations don't support C extensions. That's why we have
 # a CFFI implementation in the first place. The code here import one of our
@@ -174,7 +179,7 @@ def open(
         return fh
 
 
-def compress(data: ByteString, level: int = 3) -> bytes:
+def compress(data: Buffer, level: int = 3) -> bytes:
     """Compress source data using the zstd compression format.
 
     This performs one-shot compression using basic/default compression
@@ -192,7 +197,7 @@ def compress(data: ByteString, level: int = 3) -> bytes:
     return cctx.compress(data)
 
 
-def decompress(data: ByteString, max_output_size: int = 0) -> bytes:
+def decompress(data: Buffer, max_output_size: int = 0) -> bytes:
     """Decompress a zstd frame into its original data.
 
     This performs one-shot decompression using basic/default compression