Context

After PYTHON-3898, we can implement a check to make sure that X% of new lines of code are covered in a given PR.  We can potentially use https://github.com/Bachmann1234/diff_cover. From their docs:

"Diff coverage is the percentage of new or modified lines that are covered by tests. This provides a clear and achievable standard for code review: If you touch a line of code, that line should be covered. Code coverage is every developer's responsibility!"

Acceptance Criteria

Implement a check to make sure that X% of new lines of code are covered in a given PR.

Pitfalls

N/A