remove required keyword for 6.0 compatability

Author: msoler8785

src/SocketLabs.EventWebhooks.Extensions/Models/Inbound/Email.cs

@@ -2,7 +2,7 @@
 {
     public class Email
     {
-        public required string EmailAddress { get; set; }
+        public string EmailAddress { get; set; } = null!;
         public string? FriendlyName { get; set; }
     }
 }