chore(ci): replace arm64 image with latest

Author: Akash Satheesan

.github/workflows/ci.yaml

@@ -133,7 +133,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [ubuntu-16.04, ubuntu-arm64-16.04, macos-latest]
+        os: [ubuntu-16.04, ubuntu-arm64-latest, macos-latest]
     steps:
       - uses: actions/checkout@v2