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## 5.0.8

**`(fix):`** Eliminate Pydantic v2 deprecation warnings in `UniversalBaseModel`. Under Pydantic v2,
the class-based `Config` pattern with `smart_union` and `allow_population_by_field_name`
emits deprecation warnings. `UniversalBaseModel` now uses `model_config: ConfigDict` with
`populate_by_name=True`, `validate_by_name=True`, and `validate_by_alias=True` (for v2.11+
support) for v2, and a custom `@model_serializer` for datetime serialization instead of
the deprecated `json_encoders`. Pydantic v1 continues to use the original class-based Config.