Use Node 16 actions to remove deprecation warnings about Node 12

[irperkin]

While watching this deploy, I saw we were getting some deprecation warnings: https://github.com/onboardiq/pool/actions/runs/3267006160

Node.js 12 actions are deprecated: https://github.blog/changelog/2022-09-22-github-actions-all-actions-will-begin-running-on-node16-instead-of-node12/

I've updated the dopplerhq/cli, Azure/setup-kubectl, and aws-actions/configure-aws-credentials to reflect this. I've also updated kubectl to 1.21.0 since that's the version we're running in AWS.

The changelogs for each action and relevant info:

• dopplerhq/cli
• Azure/setup-kubectl
  • We're jumping from v1 to v3 here but the changelog doesn't seem to indicate any breaking changes.
• aws-actions/configure-aws-credentials
  • Update action to use node 16 aws-actions/configure-aws-credentials#489 (comment)