[BUG] Serialization bug with pydantic.BaseModel and multiple StructuredDataset

### Flyte & Flytekit version

Flyte 1.15.1
Flytekit 1.16.3

### Describe the bug

Flyte fails to serialize a pydantic.BaseModel with multiple StructuredDataset fields, but dataclass works.

```python
import flytekit as fl
from pydantic import BaseModel
from pydantic.dataclasses import dataclass

# This becomes an empty dict (does not work) after serialization by Flyte when used as output in a task.
class BaseModelTwo(BaseModel):
foo: fl.StructuredDataset
bar: fl.StructuredDataset

# This is serialized (works) by Flyte when used as output in a task.
@dataclass
class DataClassTwo:
foo: fl.StructuredDataset
bar: fl.StructuredDataset
```

### Expected behavior

Both `pydantic.Basemodel` and `dataclass` should work to annotate the output.

### Additional context to reproduce

One can test with these tasks.

```python
import flytekit as fl
import numpy as np
import pandas as pd

# Does not work (empty dict as output)
@fl.task
def return_basemodel_two() -> BaseModelTwo:
return BaseModelTwo(
foo=fl.StructuredDataset(dataframe=pd.DataFrame(np.random.rand(3, 3))),
bar=fl.StructuredDataset(dataframe=pd.DataFrame(np.random.rand(3, 3))),
)

# Works (returns populated dataclass as expected)
@fl.task
def return_dataclass_two() -> DataClassTwo:
return DataClassTwo(
foo=fl.StructuredDataset(dataframe=pd.DataFrame(np.random.rand(3, 3))),
bar=fl.StructuredDataset(dataframe=pd.DataFrame(np.random.rand(3, 3))),
)
```

### Screenshots

_No response_

### Are you sure this issue hasn't been raised already?

- [x] Yes

### Have you read the Code of Conduct?

- [x] Yes

Reproduce the issue with Flyte 1.15.1 and Flytekit 1.16.3 using the return_basemodel_two and return_dataclass_two tasks shown in the report. Compare serialization of BaseModelTwo and DataClassTwo with their two StructuredDataset fields; done means the BaseModel output is populated rather than an empty dict and the dataclass behavior remains working.

Written by the indexing model from the issue text.