[accounts][models] Move __unicode__ to __str__

__unicode__ is a leftover of Python 2

beat/web/accounts/models.py

@@ -71,7 +71,7 @@ class SupervisionTrack(models.Model):
     last_validation_date = models.DateTimeField(null=True, blank=True)
     supervision_key = models.CharField(max_length=40, null=True, blank=True)
 
-    def __unicode__(self):
+    def __str__(self):
         return u"Supervisor: %s, Supervisee, %s, Validity: %s" % (
             self.supervisor.username,
             self.supervisee.username,
@@ -123,8 +123,8 @@ class Profile(models.Model):
 
     objects = ProfileManager()
 
-    def __unicode__(self):
-        return u"User: %s" % self.user.username
+    def __str__(self):
+        return "User: %s" % self.user.username
 
     def _generate_current_supervision_key(self):
         length = 40