cubicweb-oaipmh #14478937 ListRecords : wrong optional and required arguments [validation pending]

metadataPrefix must be required. set must be optional.

https://www.openarchives.org/OAI/openarchivesprotocol.html#header

priorityimportant
typebug
done in0.3.0
load left0.000
closed by#62e702d5c6c6 Fix ListRecords required/optional arguments
patchFix ListRecords required/optional arguments [applied]