Add a check for clashes between an exact synonym and a label

[cmungall]

We have checks for duplicate label, duplicate exact syn, but not label=exact_syn

[cmungall]

It looks like duplicate_label_synonym is intended to catch this, but there is a typo, the last line should be entity2?

robot/robot-core/src/main/resources/report_queries/duplicate_label_synonym.rq

Lines 20 to 23 in 7a0621b

	FILTER NOT EXISTS { ?entity owl:deprecated true }
	FILTER NOT EXISTS { ?entity2 owl:deprecated true }
	?entity rdfs:label ?value .
	?entity ?property ?value .

trivial fix but wanted to check what was intended - @beckyjackson ?