fix: SQLModel table model not validated

[AlpAribal]

When using a SQLModel class with table=True as dtype, schema is not validated. This is because such SQLModel classes do not validate data at init time (see here). This PR solves this by explicitly calling model_validate/parse_obj instead of instantiating the class.

Minimal example (python=3.8 sqlmodel=0.0.19 pandera=0.19.3):

# example.py
import pandas as pd
import pandera as pa
from pandera.engines.pandas_engine import PydanticModel
from sqlmodel import SQLModel, Field

class Record(SQLModel, table=True):
    name: str = Field(primary_key=True)

class PydanticSchema(pa.DataFrameModel):
    class Config:
        dtype = PydanticModel(Record)

df = pd.DataFrame({"name": [3]})
PydanticSchema.validate(df)

Without the fix, validation succeeds while only emitting a warning from model_dump():

$ python example.py 
UserWarning: Pydantic serializer warnings:
  Expected `str` but got `int` - serialized value may not be as expected

With the fix, a SchemaError is raised:

$ python example.py 
...
pandera.errors.SchemaError: Error while coercing 'PydanticSchema' to type <class '__main__.Record'>: Could not coerce <class 'pandas.core.frame.DataFrame'> data_container into type <class '__main__.Record'>
   index failure_case
0      0  {'name': 1}