Pre-submission checklist

• I've ran the linters locally and fixed lint errors related to the files I modified in this PR. You can install the linters by running pip install -r requirements-dev.txt && pre-commit install
• pre-commit run

Summary

Fixes #827

• Run GitHub Actions tests on current versions of Python #832
• Pyre failing in python 3.8 and 3.9 due to new syntax  #827 (comment)

Our GitHub Actions tests are failing on Python < 3.10 because of the use of PEP 604 syntax.

• PEP 604 – Allow writing union types as X | Y -- https://peps.python.org/pep-0604

Test Plan

Get the GitHub Actions tests to pass.