Update GitHub actions to use Node 16

https://github.blog/changelog/2022-09-22-github-actions-all-actions-will-begin-running-on-node16-instead-of-node12/

.github/workflows/build.yml

@@ -13,7 +13,7 @@ jobs:
       matrix:
         cpu_target: [ "000", "02060", "030", "040", "060", "col" ]
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - name: Install SSH keys
         if: ${{ github.event_name == 'push' }}
         env: