fix: constrained unions

[guacs]

Description

• Fix the parsing of the constraints from union types for Pydantic v2 models
  • Before there used to be special handling of optional types, but that's not needed since optional types are also unions and so optional types should also be handled the same way as union types where we just ignore NoneType. This makes the change the same as that of FieldMeta.from_type (as changed in fix: handle unions properly #491).
• Fix the way the annotated types are handled when calling FieldMeta.from-type by using the actual type that is annotated rather than Annotated[type, ...]
  • Due to the change in FieldMeta.type_args in fix: handle unions properly #491, Annotated[List[str], MinLen(10)] now returns List[str] whereas before it would have returned str as the child. This results in the children for the FieldMeta corresponding to the annotation Annotated[List[str], MinLen(10)] to be List[str] instead of str. Unwrapping the annotation to get the actual underlying type fixes this problem since now FieldMeta.type_args will return str in this case instead of List[str].

Close Issue(s)

• Fixes Bug: Optional constrained types do not work #493

[sonarcloud]

Quality Gate failed

Failed conditions
91.7% Coverage on New Code (required ≥ 98%)

See analysis details on SonarCloud

[github-actions]

Documentation preview will be available shortly at https://litestar-org.github.io/polyfactory-docs-preview/499

[guacs]

I think the sonar code coverage issue can be ignored since the missing coverage is for the 3.8 specific code.