fix macos ci setup for apple silicon runners

Author: IanButterworth

.github/workflows/ci.yml

@@ -28,14 +28,14 @@ jobs:
           - '1.9'
         os:
           - ubuntu-latest
-          - macOS-latest
           - windows-latest
         arch:
           - x64
           - x86
-        exclude:
+        include:
           - os: macOS-latest
-            arch: x86
+            arch: aarch64
+        exclude:
           - os: windows-latest # Killing workers doesn't work on windows in 1.9
             version: '1.9'