The date needs to be in year-month-day format: https://www.w3.org/TR/2012/REC-xmlschema11-2-20120405/datatypes.html#date.
>>> from rdflib import Graph
>>> g = Graph()
>>> g.parse("https://raw.githubusercontent.com/duraspace/pcdm/refs/heads/main/models.rdf", format="xml")
ValueError: XSD Date string must contain at least two dashes
The date needs to be in
year-month-dayformat: https://www.w3.org/TR/2012/REC-xmlschema11-2-20120405/datatypes.html#date.