Get rid of Docker warnings

[jsf9k]

🗣 Description

This pull request gets rid of one warning from docker compose and two warnings from docker build.

💭 Motivation and context

• The docker-compose warning is due to the fact that the version key has been deprecated in Docker composition files.
• The docker warnings are both due to the fact that in Dockerfile the word AS should be uppercase in FROM...AS... lines.

Code without warnings is cleaner code.

🧪 Testing

All automated tests pass.

✅ Pre-approval checklist

• This PR has an informative and human-readable title.
• Changes are limited to a single goal - eschew scope creep!
• All relevant type-of-change labels have been added.
• I have read the CONTRIBUTING document.
• These code changes follow cisagov code standards.
• All new and existing tests pass.

[dav3r]

👍 👍

[lwersiy]

LGTM