fix breaking changes

Author: damienbod

AspNetCoreServiceBusApi1/StartupExtensions.cs

@@ -1,4 +1,4 @@
-using Microsoft.OpenApi.Models;
+using Microsoft.OpenApi;
 using Serilog;
 using ServiceBusMessaging;
 namespace AspNetCoreServiceBusApi1;

AspNetCoreServiceBusApi2/StartupExtensions.cs

@@ -1,7 +1,7 @@
 
 using AspNetCoreServiceBusApi2.Model;
 using Microsoft.EntityFrameworkCore;
-using Microsoft.OpenApi.Models;
+using Microsoft.OpenApi;
 using Serilog;
 using ServiceBusMessaging;