Fix tests

Author: MaggieKimani1

test/Microsoft.OpenApi.Tests/Models/OpenApiExampleTests.SerializeReferencedExampleAsV3JsonWithoutReferenceWorks_produceTerseOutput=False.verified.txt

@@ -21,6 +21,7 @@
           }
         ]
       }
-    ]
+    ],
+    "aDate": "2022-12-12"
   }
 }

test/Microsoft.OpenApi.Tests/Models/OpenApiExampleTests.SerializeReferencedExampleAsV3JsonWithoutReferenceWorks_produceTerseOutput=True.verified.txt

@@ -1 +1 @@
-{"value":{"versions":[{"status":"Status1","id":"v1","links":[{"href":"http://example.com/1","rel":"sampleRel1"}]},{"status":"Status2","id":"v2","links":[{"href":"http://example.com/2","rel":"sampleRel2"}]}]}}
+{"value":{"versions":[{"status":"Status1","id":"v1","links":[{"href":"http://example.com/1","rel":"sampleRel1"}]},{"status":"Status2","id":"v2","links":[{"href":"http://example.com/2","rel":"sampleRel2"}]}],"aDate":"2022-12-12"}}

test/Microsoft.OpenApi.Tests/Models/OpenApiExampleTests.cs

@@ -1,6 +1,7 @@
 // Copyright (c) Microsoft Corporation. All rights reserved.
 // Licensed under the MIT license. 
 
+using System;
 using System.Globalization;
 using System.IO;
 using System.Text;
@@ -95,7 +96,8 @@ public class OpenApiExampleTests
                             }
                         }
                     }
-                }
+                },
+                ["aDate"] = new OpenApiDate(DateTime.Parse("12/12/2022 00:00:00"))
             }
         };