Allow file upload in payment provider settings

src/pretix/control/templates/pretixcontrol/event/payment_provider.html

@@ -3,7 +3,7 @@
 {% load bootstrap3 %}
 {% block inside %}
     <h1>{% trans "Payment settings" %}</h1>
-    <form action="" method="post" class="form-horizontal form-plugins">
+    <form action="" method="post" class="form-horizontal form-plugins" enctype="multipart/form-data">
         {% csrf_token %}
         <fieldset>
             <legend>

src/pretix/control/views/event.py

@@ -355,6 +355,7 @@ class PaymentProviderSettings(EventSettingsViewMixin, EventPermissionRequiredMix
             obj=self.request.event,
             settingspref=self.provider.settings.get_prefix(),
             data=(self.request.POST if self.request.method == 'POST' else None),
+            files=(self.request.FILES if self.request.method == 'POST' else None),
             provider=self.provider
         )
         form.fields = OrderedDict(