Github Actions workflow maintenance

[hsorby]

The deployment script we use with Github actions is raising some warnings. We should address these warnings before they become errors.

The 67 warnings we currently receive boil down to these two issues:

• https://github.blog/changelog/2022-10-11-github-actions-deprecating-save-state-and-set-output-commands/
• https://github.blog/changelog/2022-09-22-github-actions-all-actions-will-begin-running-on-node16-instead-of-node12/