Changes

Hotfix:Add @PodamExclude to entity relations

Annotate bidirectional JPA relationships with @PodamExclude to avoid Podam populating cyclic references and potential recursion in toString. Changes: PetEntity - import PodamExclude and mark vaccinationRecords and shelter fields; VaccinationRecordEntity - add @NoArgsConstructor and @AllArgsConstructor, import PodamExclude, and mark pet and vaccines fields; VaccineEntity - import ToString and PodamExclude and mark vaccinationRecord field (also exclude from toString). Minor import adjustments included.
 (commit: 943f7a8)