[CHORE]: Remove unused optional dependency `graphlib_backport`

[hesreallyhim]

Description of changes

In pyproject.toml, there is a conditional import for graphlib_backport for python<3.9. But "requires-python" is ">=3.9". So this conditional installation can never be triggered, so I removed it. Maybe there is a reason you keep it around, but it seemed redundant to me.

Also, I added types-jsonschema to requirements_dev.txt because I was getting missing stub warnings around jsonschema.

Test plan

How are these changes tested?

I built the project locally with the dependency changes.

• [ ] Tests pass locally with pytest for python, yarn test for js, cargo test for rust

Documentation Changes

Are all docstrings for user-facing APIs updated if required? Do we need to make documentation changes in the docs repository?

[github-actions[bot]]

Reviewer Checklist

Please leverage this checklist to ensure your code review is thorough before approving

Testing, Bugs, Errors, Logs, Documentation

• [ ] Can you think of any use case in which the code does not behave as intended? Have they been tested?
• [ ] Can you think of any inputs or external events that could break the code? Is user input validated and safe? Have they been tested?
• [ ] If appropriate, are there adequate property based tests?
• [ ] If appropriate, are there adequate unit tests?
• [ ] Should any logging, debugging, tracing information be added or removed?
• [ ] Are error messages user-friendly?
• [ ] Have all documentation changes needed been made?
• [ ] Have all non-obvious changes been commented?

System Compatibility

• [ ] Are there any potential impacts on other parts of the system or backward compatibility?
• [ ] Does this change intersect with any items on our roadmap, and if so, is there a plan for fitting them together?

Quality

• [ ] Is this code of a unexpectedly high quality (Readability, Modularity, Intuitiveness)

[propel-code-bot[bot]]

This PR removes the unused conditional dependency graphlib_backport from pyproject.toml and requirements.txt, as Python <3.9 is no longer supported by the project. It also adds types-jsonschema to requirements_dev.txt to address missing stubs for jsonschema during development.

This summary was automatically generated by @propel-code-bot

[hesreallyhim]

@HammadB i know this is older than gpt-3 but i just updated the branch, can we merge or close? preference being to merge 🙏 lol