add bg traits to study.ts

Author: ala-ebi

src/app/core/models/study.ts

@@ -30,6 +30,7 @@ export interface Study {
   agreedToCc0: boolean;
   diseaseTrait: ReportedTrait;
   efoTraits: EfoTrait[];
+  backgroundEfoTraits: EfoTrait[];
   sumstats_flag: boolean;
   pooled_flag: boolean;
   gxe_flag: boolean;