Parses module in more robust way for fn gathering

[elijahbenizzy]

inspect.getmodule(fn) depends on the state of sys.modules. This can break if you're doing repeated parsing -- E.G. running it then wiping sys.modules. Instead, we can just ask the function for its module. It's simpler, and won't break.

[Short description explaining the high-level reason for the pull request]

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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.