Add eMail-Template for free approval orders (#1750)

Co-authored-by: Felix Rindt <felix@rindt.me>

src/pretix/base/services/orders.py

@@ -258,7 +258,7 @@ def approve_order(order, user=None, send_mail: bool=True, auth=None, force=False
     if send_mail:
         with language(order.locale):
             if order.total == Decimal('0.00'):
-                email_template = order.event.settings.mail_text_order_free
+                email_template = order.event.settings.mail_text_order_approved_free
                 email_subject = _('Order approved and confirmed: %(code)s') % {'code': order.code}
             else:
                 email_template = order.event.settings.mail_text_order_approved

src/pretix/base/settings.py

@@ -1419,6 +1419,19 @@ You can select a payment method and perform the payment here:
 
 {url}
 
+Best regards,
+Your {event} team"""))
+    },
+    'mail_text_order_approved_free': {
+        'type': LazyI18nString,
+        'default': LazyI18nString.from_gettext(gettext_noop("""Hello,
+
+we approved your order for {event} and will be happy to welcome you
+at our event. As you only ordered free products, no payment is required.
+
+You can change your order details and view the status of your order at
+{url}
+
 Best regards,
 Your {event} team"""))
     },