Make DB id's nullable

src/Server/Entities/JobListing.cs

@@ -1,7 +1,7 @@
 namespace BoredCareers.Entities {
 
     public class JobListing {
-        public int ID { get; set; } // PK
+        public int? ID { get; set; } // PK
         public int CompanyID { get; set; } // FK
         public string Title { get; set; } = "";
         public string PostalCode { get; set; } = "";