Updated not_member_of operator to NotMemberOf#592

oneeb-nhs wants to merge 1 commit intomainNHSDigital/eligibility-signposting-api:mainfrom

eli-673/update-not_member_of-operatorNHSDigital/eligibility-signposting-api:eli-673/update-not_member_of-operatorCopy head branch name to clipboard