fix referrer link in admin

lambdainst/admin.py

@@ -43,14 +43,13 @@ class VPNUserInline(admin.StackedInline):
         if not object.referrer:
             return "-"
 
-        s = make_user_link(object.referrer) + " "
         if object.referrer_used:
-            s += _("(rewarded)")
+            status = _("(rewarded)")
         else:
-            s += _("(not rewarded)")
-        return s
+            status = _("(not rewarded)")
+
+        return format_html("{} {}", make_user_link(object.referrer), status)
 
-    referrer_a.allow_tags = True
     referrer_a.short_description = _("Referrer")
 
     def is_paid(self, object):