Implement deserialize for HSGP classes

[wd60622]

The HSGP classes are not supported in the deserialize function. They do have the to/from_dict methods but that structure might want to be replaced to a format that is more similar to the fourier classes. Reference:

pymc-marketing/pymc_marketing/mmm/fourier.py

Lines 694 to 706 in 10c40ec

	def to_dict(self) -> dict[str, Any]:
	"""Serialize the Fourier seasonality.
	Returns
	-------
	dict[str, Any]
	Serialized Fourier seasonality
	"""
	return {
	"class": self.__class__.__name__,
	"data": self.model_dump(mode="json"),
	}

This PR #1315 would be a good reference for how to implement this.