chore: Remove pydantic dependency

[mac01021]

Description

Insert your PR description here. Thanks for contributing to pyQuil! 🙂

Checklist

• [ ] The PR targets the master branch
• [ ] The above description motivates these changes.
• [ ] The change is atomic and can be described by a single commit (your PR will be squashed on merge).
• [ ] All changes to code are covered via unit tests.
• [ ] Parameters and return values have type hints with PEP 484 syntax.
• [ ] Functions and classes have useful Sphinx-style docstrings.
• [ ] (New Feature) The docs have been updated accordingly.
• [ ] (Bugfix) The associated issue is referenced above using auto-close keywords.

[MarquessV]

If you rebase your branch, you should hopefully pull in a fix for the failed test check.