tf: handle type embedding in DescrptSeR.serialize

[github-actions]

not sure how to handle type embedding - type embedding is not a model parameter,
but instead a part of the input data. Maybe the interface should be refactored...

Line: 769

deepmd-kit//deepmd/tf/descriptor/se_r.py

Lines 766 to 776 in 4d347ec

	raise NotImplementedError("spin is unsupported")
	assert self.davg is not None
	assert self.dstd is not None
	# TODO: tf: handle type embedding in DescrptSeR.serialize
	# not sure how to handle type embedding - type embedding is not a model parameter,
	# but instead a part of the input data. Maybe the interface should be refactored...
	return {
	"@class": "Descriptor",
	"type": "se_r",
	"@version": 1,
	"rcut": self.rcut,