Fix Kotlin models with no properties

Author: abnegate

templates/kotlin/src/main/kotlin/io/appwrite/models/Model.kt.twig

@@ -6,6 +6,9 @@ import com.google.gson.annotations.SerializedName
 /**
  * {{ definition.description }}
  */
+{% if definition.properties | length == 0 %}
+class {{ definition.name | caseUcfirst }} {}
+{% else %}
 data class {{ definition.name | caseUcfirst }}(
 {% for property in definition.properties %}
     /**
@@ -59,4 +62,5 @@ data class {{ definition.name | caseUcfirst }}(
 {% endfor %}
 {% endif %}
 {% endfor %}
-}
+}
+{% endif %}