chore(ci): add informational Codecov status checks

[thomasrockhu-codecov]

Description

Hi, Tom from Codecov here. I noticed that you were using Codecov but weren't actually getting any notifications on pull requests. I figured it would be useful to get some idea if code being changed is being tested, but also not blocking CI/merging. Let me know if this makes sense or if we can do something that would be helpful.

Checklist:

• I have followed the Contribution Guidelines
• I have added test code and data to prove that my code functions correctly
• I have verified that new and existing tests pass locally with my changes
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation

[kaydeearts]

Thank you for your contribution! We'll try this out 👍