fix: set 'order' default value to empty list (#278)

Author: aallam

client/src/commonMain/kotlin/com/algolia/search/model/rule/FacetValuesOrder.kt

@@ -10,7 +10,7 @@ public data class FacetValuesOrder(
     /**
      * Pinned order of facet values.
      */
-    @SerialName(KeyOrder) public val order: List<String>,
+    @SerialName(KeyOrder) public val order: List<String> = emptyList(),
     /**
      * How to display the remaining items.
      */