fix: resolve conflicting exception guidance in __dlpack__

PR-URL: #887
Closes: #831

Author: kgryte

src/array_api_stubs/_2023_12/array_object.py

@@ -364,7 +364,7 @@ def __dlpack__(
             ``__dlpack__`` to return a capsule referencing an array whose underlying memory is
             accessible to the Python interpreter (represented by the ``kDLCPU`` enumerator in DLPack).
             If a copy must be made to enable this support but ``copy`` is set to ``False``, the
-            function must raise ``ValueError``.
+            function must raise ``BufferError``.
 
             Other device kinds will be considered for standardization in a future version of this
             API standard.

src/array_api_stubs/_draft/array_object.py

@@ -364,7 +364,7 @@ def __dlpack__(
             ``__dlpack__`` to return a capsule referencing an array whose underlying memory is
             accessible to the Python interpreter (represented by the ``kDLCPU`` enumerator in DLPack).
             If a copy must be made to enable this support but ``copy`` is set to ``False``, the
-            function must raise ``ValueError``.
+            function must raise ``BufferError``.
 
             Other device kinds will be considered for standardization in a future version of this
             API standard.