Github Actions Workflows should be updated to use Node.js 16 for checkout step

[ni-jfitzger]

Description of issue

Our nimibot runner summaries are showing annotations:

system_test (niscope)
Node.js 12 actions are deprecated. Please update the following actions to use Node.js 16: actions/checkout@v2. For more information see: https://github.blog/changelog/2022-09-22-github-actions-all-actions-will-begin-running-on-node16-instead-of-node12/.

We should update our configuration to use Node.js 16, before support for Node.js 12 is dropped entirely.

The configuration for this can be found in .github\workflows\github_actions_aws_*.yml (the * is a wildcard not part of a filename).
The step looks like:

    steps:
      - name: checkout repository
        uses: actions/checkout@v2

[ni-jfitzger]

According to the changelog v3 is the earliest version supporting Node.js 16. The latest released version for the action is currently v3.5.0.

The change that updated to use Node.js 16 mentioned "This is supported on all Actions Runners v2.285.0 or later." It's not clear to me if this means will need to update the version of software that our runners connect with. I guess we should try just updating the workflow files and if it works, it works.