building arm64 wheels with cibuildwheel (uses intel runner)

Temporary fix until https://github.com/github/roadmap/issues/528 is merged

pyproject.toml

@@ -11,6 +11,9 @@ test-command = [
 # Disable building PyPy wheels on all platforms
 skip = "pp*"
 
+# Skip trying to test arm64 builds on Intel Macs
+test-skip = "*-macosx_arm64 *-macosx_universal2:arm64"
+
 [tool.cibuildwheel.linux]
 # beware: the before-all script does not persist environment variables!
 # No point in defining $PATH or $CCACHE_DIR
@@ -28,5 +31,13 @@ before-all = [
   "brew install libpng",
   "brew deps --tree --installed",
 ]
+
+# TEMP while Github Actions does not provide an Apple Silicon runner
+# TODO Simply remove it when it's available
+archs = ["x86_64", "arm64"]
+before-build = [
+  "ccache -s",
+  "bash {project}/ci-scripts/macos/libpng-patch.sh",
+]
 # Repair macOS wheels (include libpng with the wheel, for example)
 repair-wheel-command = "delocate-wheel --require-archs {delocate_archs} -w {dest_dir} -v --ignore-missing-dependencies {wheel}"