Serialize CalendarDate and Date Parameters with their timezone info?

CalendarDate serializes with `value.strftime("%Y-%m-%d")` and Date with `value.strftime("%Y-%m-%dT%H:%M:%S.%f")`. These two formats don't include any timezone info while they include the time offset, e.g. as in `2022-05-11T17:33:14+02:00`. I would think this would be an improvement to Param, however I'm not sure about the consequences on GUI libraries using Param like Panel, which would then have to deal with timezone infos to set the values of their date-related widgets.