Simplify the format of problem number.

Author: lukaskogaborik

bullet/problems/templates/archive/problems.html

@@ -24,8 +24,7 @@ <h2 class="text-2xl md:text-4xl mt-4 mb-4 md:mb-16">{{ competition.name }}</h2>
     {% for problem in object_list %}
         <article class="my-8 max-w-prose mx-auto px-2">
             <h2 class="font-bold text-lg">
-                {% problem_number problem categories as problem_number %}
-                {% blocktranslate with n=problem_number %}Problem {{ n }}{% endblocktranslate %}
+                {% blocktranslate with n=problem.problem.number %}Problem {{ n }}{% endblocktranslate %}
             </h2>
             <div class="prose prose-archive">
                 {{ problem.statement|safe }}