Revert typing.Literal and import it outside the TYPE_CHECKING block

[frost-nzcr4]

Change Summary

In PR #7680 the typing.Literal was replaced with typing_extensions.Literal. I was curious enough to double-check the origin and found that the error was caused by importing from typing import Literal inside the TYPE_CHECKING block but then using it outside the scope.

I suggest to revert typing.Literal back, but importing it correctly at the module level. This meets the required Python 3.8+ limitation and works well with the example from the original issue:

import typing
from pydantic import BaseModel
typing.get_type_hints(BaseModel.model_copy)
typing.get_type_hints(BaseModel.model_dump)
typing.get_type_hints(BaseModel.dict)

Related issue number

refs #7623

Checklist

• The pull request title is a good summary of the changes - it will be used in the changelog
• Unit tests for the changes exist
• Tests pass on CI
• Documentation reflects the changes where applicable
• My PR is ready to review, please add a comment including the phrase "please review" to assign reviewers

Selected Reviewer: @dmontagu

[frost-nzcr4]

please review

[codspeed-hq]

CodSpeed Performance Report

Merging #9232 will not alter performance

_{Comparing frost-nzcr4:7623-use-stdlib-literal (3dadce2) with main (6aab43e)}

Summary

✅ 13 untouched benchmarks

[sydney-runkle]

Looks great, thanks!