Mark constructor parameters of exceptions as positional-only

[Viicos]

Change Summary

As these exceptions also inherit from ValueError, providing keyword arguments fails when the super().__new__ call is performed (ValueError only takes positional arguments). Generally, I also tend to enforce pos-only args for exceptions, otherwise the default repr doesn't show the argument:

class MyExc(Exception):
    def __init__(self, message: str) -> None:
        self.message = message

str(MyExc('test'))
# 'test'
str(MyExc(message='test'))
# ''

Also clean up the stub file a bit: avoid duplicating __new__ and __init__ (at runtime, __new__ is the one actually defined but it doesn't play well with mkdocstrings), unify docstrings in classes.

Fixes pydantic/pydantic#10604.

Related issue number

Checklist

• Unit tests for the changes exist
• Documentation reflects the changes where applicable
• Pydantic tests pass with this pydantic-core (except for expected changes)
• My PR is ready to review, please add a comment including the phrase "please review" to assign reviewers

[codspeed-hq]

CodSpeed Performance Report

Merging #1699 will not alter performance

_{Comparing exc-pos-only (f50d17f) with main (3414703)}

Summary

✅ 157 untouched benchmarks

[davidhewitt]

Thanks!