setup.py: removed now-unnecessary libclang version restriction on macos-arm64.

Author: julian-smith-artifex-com

setup.py

@@ -1400,9 +1400,6 @@ def platform_release_tuple():
             ret.append(libclang)
         elif openbsd:
             print(f'OpenBSD: libclang not available via pip; assuming `pkg_add py3-llvm`.')
-        elif darwin and platform.machine() == 'arm64':
-            print(f'MacOS/arm64: forcing use of libclang 16.0.6 because 18.1.1 known to fail with `clang.cindex.TranslationUnitLoadError: Error parsing translation unit.`')
-            ret.append('libclang==16.0.6')
         elif darwin and platform_release_tuple() < (18,):
             # There are still of problems when building on old macos.
             ret.append('libclang==14.0.6')