Add missing listed_price to item variation

Author: robbi5

libpretixsync/src/main/java/eu/pretix/libpretixsync/db/AbstractItem.java

@@ -312,6 +312,7 @@ public List<ItemVariation> getVariations() throws JSONException {
             v.setDescription(variation.optJSONObject("description"));
             v.setPosition(variation.getLong("position"));
             v.setPrice(new BigDecimal(variation.getString("price")));
+            v.setListed_price(new BigDecimal(variation.getString("price")));
             v.setServer_id(variation.getLong("id"));
             v.setValue(variation.getJSONObject("value"));
             v.setAvailable_from(variation.optString("available_from"));