Mapeathor

Testing update in CI workflow

This release includes the following new features:
* Blank nodes in objects
* Empty prefix
* Language tags
* Graph maps

And the next bugs have been fixed:
* Correct quotes for IRIs in objects
* Datatypes when termtype is IRI or BlankNode

The following errors have been fixed:
* Iterator format for json/xml sources
* Allowed subject without class
* In Functions:
* Correct finding of source
* No error shown when there are functions in sheet but not referenced
* IRI type in Function Map
* Correct formating when referencing functions from function maps

Quotes in constant predicates are fixed

Support to blank nodes in subjects added

Test versioning