chore(core): Fix circular import causing tests to fail

packages/core/src/entity/product-variant/product-variant-price.entity.ts

@@ -2,8 +2,9 @@ import { CurrencyCode } from '@vendure/common/lib/generated-types';
 import { DeepPartial, ID } from '@vendure/common/lib/shared-types';
 import { Column, Entity, Index, ManyToOne } from 'typeorm';
 
-import { CustomProductVariantPriceFields, HasCustomFields } from '../..';
+import { HasCustomFields } from '../../config/custom-field/custom-field-types';
 import { VendureEntity } from '../base/base.entity';
+import { CustomProductVariantPriceFields } from '../custom-entity-fields';
 import { EntityId } from '../entity-id.decorator';
 import { Money } from '../money.decorator';