test: add missing xml spector test (microsoft#10436)

fixes: microsoft#9840

Author: jorgerangel-msft

packages/http-client-csharp/generator/TestProjects/Spector.Tests/Http/Payload/Xml/XmlTests.cs

@@ -390,6 +390,18 @@ public Task GetModelWithDatetime() => Test(async (host) =>
             Assert.AreEqual(DateTimeOffset.Parse("Fri, 26 Aug 2022 14:38:00 GMT"), model.Rfc7231);
         });
 
+        [SpectorTest]
+        public Task PutModelWithDatetime() => Test(async (host) =>
+        {
+            var model = new ModelWithDatetime(
+                DateTimeOffset.Parse("2022-08-26T18:38:00Z"),
+                DateTimeOffset.Parse("Fri, 26 Aug 2022 14:38:00 GMT"));
+            var response = await new XmlClient(host, null).GetModelWithDatetimeValueClient()
+                .PutAsync(model);
+
+            Assert.AreEqual(204, response.GetRawResponse().Status);
+        });
+
         [SpectorTest]
         public Task GetXmlErrorValue() => Test((host) =>
         {