Validate the opening_hours syntax on the opening_hours:covid19 tag

[francois2]

The usage of the tag opening_hours:covid19 is growing ​https://taginfo.openstreetmap.org/keys/opening_hours%3Acovid19#overview. Some people are using it but they are doing some mistakes with the syntax, like everyone.

I would love if the syntax of opening_hours:covid19 was checked by the the opening_hours validator.