Changes to Add new activity type

the allOf[subschema #2]/data/add_time response's property format changed from datetime to date-time for status 200

the allOf[subschema #2]/data/update_time response's property format changed from datetime to date-time for status 200

removed the media type application/x-www-form-urlencoded from the request body

added the media type application/json to the request body