Adds header to requirements.txt for s3-based deploy option

[elijahbenizzy]

Once we looked at the wheel these were missing

Changes

• license to a requirements.txt file
• license to the README
• license to .asf.yaml

How I tested this

Notes

Checklist

• PR has an informative and human-readable title (this will be pulled into the release notes)
• Changes are limited to a single goal (no scope creep)
• Code passed the pre-commit check & code is left cleaner/nicer than when first encountered.
• Any change in functionality is tested
• New functions are documented (with a description, list of inputs, and expected output)
• Placeholder code is flagged / future TODOs are captured in comments
• Project documentation has been updated if adding/changing functionality.

[github-actions]

A preview of 6e8411a is uploaded and can be seen here:

✨ https://burr.dagworks.io/pull/601 ✨

Changes may take a few minutes to propagate. Since this is a preview of production, content with draft: true will not be rendered. The source is here: https://github.com/apache/burr/tree/gh-pages/pull/601/