Flake8: fix F821 undefined name 'unicode'

cubicweb_person/schema.py

@@ -3,10 +3,7 @@ from yams.buildobjs import (EntityType, SubjectRelation, String, RichString,
 from yams.reader import context
 from cubicweb.schema import RRQLExpression, RQLConstraint
 
-try:
-    from cubicweb import _
-except ImportError:
-    _ = unicode
+from cubicweb import _
 
 
 class Person(EntityType):