Unify color of shift checkin button

shiftregister/team/templates/shift_detail.html

@@ -32,7 +32,7 @@
             </div>
             <div class="buttons">
 {% if reg.is_pending %}
-                <a class="button is-warning is-small" href="{% url 'team:checkin' reg.pk %}">Als angekommen markieren</a>
+                <a class="button is-success is-small" href="{% url 'team:checkin' reg.pk %}">Als angekommen markieren</a>
                 <a class="button is-warning is-small" href="{% url 'team:unregister' reg.pk %}">Helfer*in abmelden</a>
                 <a class="button is-danger is-small" href="{% url 'team:mark_as_failed' reg.pk %}">Nicht angetreten</a>
 {% elif reg.is_checked_in %}