codemeta: Workaround pyld issue for compact operation

pyld is not correctly loading json-ld content from http*://schema.org
(see https://github.com/digitalbazaar/pyld/issues/154) and raises an
exception when attempting to compact a codemeta document having
schema.org in its @context list.

As a workaround, remove schema.org from the @context list of a codemeta
document before compacting it.