[Minor] Fixed unclosed h2 tag (#3267)

payments/templates/pages/payment-success.html

@@ -3,7 +3,7 @@
 {% block title %}{{ _("Payment Success") }}{% endblock %}
 
 {%- block header -%}
-<h2>{{ _("Payment Success") }}<h2>
+<h2>{{ _("Payment Success") }}</h2>
 {% endblock %}
 
 {%- block page_content -%}