Fixed all relationship and write errors in all entities

PyroFetes/Models/City.cs

@@ -0,0 +1,12 @@
+using System.ComponentModel.DataAnnotations;
+
+namespace PyroFetes.Models;
+
+public class City
+{
+    [Key] public int Id  { get; set; }
+    [Required, MaxLength(100)] public string? Name  { get; set; }
+    [Required] public int ZipCode { get; set; }
+    
+    public List<Show>? Shows { get; set; }
+}