0.5.1: correct merge error

The print statement introduced in the merge commit
needed to be converted to a `return` in the new
formatting strategy.

src/omero_rdf/__init__.py

@@ -137,7 +137,7 @@ def __init__(self):
     def serialize_triple(self, triple):
         s, p, o = triple
         escaped = o.n3().encode("unicode_escape").decode("utf-8")
-        print(f"""{s.n3()}\t{p.n3()}\t{escaped} .""")
+        return f"""{s.n3()}\t{p.n3()}\t{escaped} ."""
 
 
 class NonStreamingFormat(Format):