ImportError while loading conftest '/build/python-rdflib/src/RDFLib-rdflib-6ed2ef4/test/conftest.py'.
test/conftest.py:1: in <module>
    from .earl import EarlReporter
test/earl.py:8: in <module>
    from test.manifest import RDFT
test/manifest.py:3: in <module>
    from rdflib import RDF, RDFS, Graph, Namespace
rdflib/__init__.py:158: in <module>
    from rdflib.term import URIRef, BNode, Literal, Variable
rdflib/term.py:47: in <module>
    from isodate import (
E   ModuleNotFoundError: No module named 'isodate'
==> ERROR: A failure occurred in check().
    Aborting...