Upstream Pydantic 2.12.0 has a Regression that will break PyIceberg

### Apache Iceberg version

None

### Please describe the bug 🐞

Pydantic recently `2.12.0` and unfortunately it contains a regression: https://github.com/pydantic/pydantic/issues/12347 that `ValidationInfo` object will lose `field_names` in some cases.

I have a draft PR that experiments `2.12.0` and confirmed that the regression affect us: https://github.com/apache/iceberg-python/pull/2589
```

table_metadata = ValidationInfo(config={'title': 'TableMetadataV2', 'validate_by_alias': True, 'validate_by_name': True}, context=None, data=None, field_name=None)

    def check_schemas(table_metadata: TableMetadata) -> TableMetadata:
        """Check if the current-schema-id is actually present in schemas."""
>       current_schema_id = table_metadata.current_schema_id
E       AttributeError: 'pydantic_core._pydantic_core.ValidationInfo' object has no attribute 'current_schema_id'
```

More info:
`pydantic 2.11.10`

<img width="1993" height="655" alt="Image" src="https://github.com/user-attachments/assets/90ae0cf4-d3fa-4d50-b94c-b1c8e791eae1" />

`pydantic 2.12.0`

<img width="2011" height="474" alt="Image" src="https://github.com/user-attachments/assets/a5e6f745-0054-46c3-9201-459499999ee9" />

While waiting for upstream fix, I think we may want to pin the pydantic version to `<2.12.0`


### Willingness to contribute

- [ ] I can contribute a fix for this bug independently
- [ ] I would be willing to contribute a fix for this bug with guidance from the Iceberg community
- [ ] I cannot contribute a fix for this bug at this time

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