Fix compatibility with Symfony 4.3 (#311)

* Fix compatibility with Symfony 4.3

The block name change from panelContent to panel

* Prevents BC break

From symfony/web-profiler-bundle@a92e0ba#diff-3e3f9f89f28a037c50c1714c5a21b3c4

Author: albingi

Resources/views/SymfonyProfiler/translation.html.twig

@@ -120,6 +120,10 @@
     {% include "@Translation/SymfonyProfiler/javascripts.html.twig" %}
 {% endblock %}
 
+{% block panel %}
+    {{ block('panelContent') }}
+{% endblock %}
+
 {% macro render_table(messages, checkedByDefault = false) %}
     <table>
         <thead>