python3.9: enable for clangarm64

Need a pending package in queue to test, and this is a good candidate.

mingw-w64-python3.9/PKGBUILD

@@ -32,7 +32,7 @@ pkgver=${_pybasever}.6
 pkgrel=3
 pkgdesc="A high-level scripting language (mingw-w64)"
 arch=('any')
-mingw_arch=('mingw32' 'mingw64' 'ucrt64' 'clang64' 'clang32')
+mingw_arch=('mingw32' 'mingw64' 'ucrt64' 'clang64' 'clang32' 'clangarm64')
 license=('PSF')
 url="https://www.python.org/"
 depends=("${MINGW_PACKAGE_PREFIX}-gcc-libs"