Add aarch64 CI job

Author: ictrobot

.github/workflows/rust.yaml

@@ -14,6 +14,7 @@ jobs:
         target:
           - x86_64-unknown-linux-gnu
           - i686-unknown-linux-gnu
+          - aarch64-unknown-linux-gnu
           - s390x-unknown-linux-gnu # Big-endian
     env:
       CARGO_CMD: "${{ matrix.target == 'x86_64-unknown-linux-gnu' && 'cargo' || 'cross' }}"