feat: add aarch64 support

Author: gilesw

.github/workflows/test.yml

@@ -22,6 +22,9 @@ jobs:
           - os: macos-latest
             target: x86_64-apple-darwin
 
+          - os: macos-latest
+            target: aarch64-apple-darwin
+
     steps:
     - name: Checkout repository
       uses: actions/checkout@v2
@@ -37,4 +40,4 @@ jobs:
         target: ${{ matrix.target }}
 
     - name: Test
-      run: cargo test
+      run: cargo test