Peptidoform properties: `TagBase` vs `ModificationBase`?

[RalfG]

Should these be TagBase instead of ModificationBase? They could be MassModification, which is TagBase, but not ModificationBase.

psm_utils/psm_utils/peptidoform.py

Lines 621 to 630 in 19a657d

	class PeptidoformProperties(TypedDict):
	"""Property items of a :py:class:`Peptidoform`."""
	n_term: list[proforma.ModificationBase] | None
	c_term: list[proforma.ModificationBase] | None
	unlocalized_modifications: list[proforma.ModificationBase]
	labile_modifications: list[proforma.ModificationBase]
	fixed_modifications: list[proforma.ModificationRule]
	charge_state: proforma.ChargeState
	isotopes: list[proforma.StableIsotope]