Error when using filter on Luxon object

[AAllport]

When using the filter on a luxon object, the error here gets triggered https://github.com/casbloem/vue-luxon/blob/1c59c7002dc6e48aa93ba47987bd4f79055a1112/src/main.js#L9

Take the following code: {{ dates.selected | luxon }} where dates.selected is an instance of DateTime. An error is thrown since DateTime does not have .value

Please can we consider adding support for adding the filter to instances of DateTime, as this feels like a fairly reasonable use-case in a strongly typed VueJs application?