Cannot install cwltool because ... rdflib-jsonld version

[mccalluc]

ERROR: Cannot install cwltool because these package versions have conflicting dependencies.

The conflict is caused by:
    schema-salad 4.5.20191229160203 depends on rdflib-jsonld<0.5.0 and >=0.3.0
    schema-salad 4.5.20191204060541 depends on rdflib-jsonld<0.5.0 and >=0.3.0
    schema-salad 4.5.20191203162929 depends on rdflib-jsonld<0.5.0 and >=0.3.0
    schema-salad 4.5.20191023134839 depends on rdflib-jsonld<0.5.0 and >=0.3.0
    schema-salad 4.5.20191017101802 depends on rdflib-jsonld<0.5.0 and >=0.3.0
    schema-salad 4.5.20190906201758 depends on rdflib-jsonld<0.5.0 and >=0.3.0
    schema-salad 4.5.20190815125611 depends on rdflib-jsonld<0.5.0 and >=0.3.0
    schema-salad 4.5.20190729164411 depends on rdflib-jsonld<0.5.0 and >=0.3.0
    schema-salad 4.5.20190621200723 depends on rdflib-jsonld<0.5.0 and >=0.3.0

To fix this you could try to:
1. loosen the range of package versions you've specified
2. remove package versions to allow pip attempt to solve the dependency conflict

Originally posted by @mccalluc in #88 (comment)