Add the --non-interactive flag when installing type stubs via mypy

[jsf9k]

🗣 Description

This pull reques

• Adds the --non-interactive flag when installing type stubs via mypy
• Moves the mypy command toward the end of the setup-env script

💭 Motivation and context

• This flag forces mypy to hide the errors about missing stubs and instead simply install stubs without asking for confirmation. It also does not return an error code, which it does without this flag even if you opt to let it install the missing type stubs.
• Moving the mypy command toward the end of the setup-env script ensures that, should the command fail, all the other good stuff in the script will still happen.

🧪 Testing

All automated tests pass. These changes were tested as part of cisagov/cyhy-config#5.

✅ 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]

I'm on board with this change. 👍