Adds 3.10 tests

[skrawcz]

We should be able to support 3.10 without making any changes. This commit adds circleci checks for this.

Changes

• No functional changes
• Adds to circleci config to test 3.10 environment.

How I tested this

• ran locally

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.

[elijahbenizzy]

We should start deprecating 3.6 eventually?