procedure schema does not contain validTime

[ricardogsilva]

Part 1 of the standard describes Procedures as having an optional validTime attribute (Table 14):

https://docs.ogc.org/is/23-001/23-001.html#_10ca3989-ba00-3c03-fb4d-56f97f29557b

and again in the GeoJSON encodings, Table 44:

https://docs.ogc.org/is/23-001/23-001.html#_req_geojson_procedure-mappings

However, the schema in procedure.json does not mention validTime anywhere.

[alexrobin]

Yes, I see that. This is an error. I think we used to have the validTime property on the base feature schema. When we moved this property to the more specialized system.json, we forgot to also add it to procedure.json.