fix tests

bookshop/srv/cat-service.cds

@@ -8,7 +8,7 @@ service CatalogService @(path:'/browse') {
   /** For display in details pages */
   @readonly entity Books as projection on my.Books { *,
     author.name as author
-  } excluding { createdBy, modifiedBy };
+  } excluding { createdBy, modifiedBy, contents };
 
   @requires: 'authenticated-user'
   action submitOrder ( book: Books:ID, quantity: Integer ) returns { stock: Integer };