Improve validation for date representation

[ThomasPO]

DateTime representation typed "Date" is validated using regular expression. This implementation accepts non-valid date as 30th of February 2020.

Would it be interesting to add a cast to identify these cases at runtime. For instance:

rule_date_report : match_characters(cast(date_report, date), "^\d{4}-(((0)[0-9])|((1)[0-2]))-([0-2][0-9]|(3)[0-1])$") errorcode "Date format YYYY-MM-DD not valid";