CI: Skip tests when buildling aarch64 wheels, to avoid compiling numpy

.ci/build_wheels.sh

@@ -21,14 +21,20 @@ export CIBW_TEST_REQUIRES="cython pytest numpy nibabel coverage cython-coverage
 # history [GHA logs of failing builds deleted]).
 export CIBW_SKIP="pp*"
 
-# Skip i686 tests - I have experienced hangs on these
-# platforms, which I traced to a trivial numpy operation -
-# "numpy.linalg.det(numpy.eye(3))". This occurs when numpy
-# has to be compiled from source during the build, so can
-# be re-visited if/when numpy is avaialble on all platforms.
+# Skip i686 and aarch64 tests
+
+#  - I have experienced hangs on these platforms,
+#    which I traced to a trivial numpy operation -
+#    "numpy.linalg.det(numpy.eye(3))".
+
+#  - Numpy wheels are not available for these
+#    platforms, so has to be compiled from source
+#    during the build, which massively increases
+#    build time and complexity.
 #
-# Skip py312 tests on Windows due to unresolved test failures.
-export CIBW_TEST_SKIP="*i686* cp312-win*"
+# Skip py312 tests on Windows due to unresolved
+# test failures.
+export CIBW_TEST_SKIP="*i686* *aarch64* cp312-win*"
 
 # Pytest makes it *very* awkward to run tests
 # from an installed package, and still find/