Changes to POST /api/v1/projects/:project_id/issues/:ref/actions/unassign

added the optional property issue/accountable_actor to the response with the 200 status

added the optional property issue/authority_uid to the response with the 200 status

added the optional property issue/source_actor to the response with the 200 status

added the optional property issue/teammate to the response with the 200 status

added the optional property issue/verification to the response with the 200 status

added the optional property issue/assignment_expires_on to the response with the 200 status

added the new optional request property expected_owner

the request property actor became optional