fix: updated the UploadSession model to implement IUploadSession from the core package.

Author: Andrew Omondi

src/Microsoft.Graph/Extensions/UploadSession.cs

@@ -0,0 +1,6 @@
+namespace Microsoft.Graph.Beta.Models
+{
+    public partial class UploadSession : Microsoft.Graph.IUploadSession
+    {
+    }
+}

tests/Microsoft.Graph.DotnetCore.Test/Models/Extensions/UploadSessionTests.cs

@@ -0,0 +1,17 @@
+using Microsoft.Graph.Beta.Models;
+using Xunit;
+
+namespace Microsoft.Graph.DotnetCore.Test.Extensions;
+
+public class UploadSessionTests
+{
+    [Fact]
+    public void AddPublicEncryptionCertificate()
+    {
+        // arrange 
+        var uploadSession = new UploadSession();
+
+        // act
+        Assert.IsAssignableFrom<IUploadSession>(uploadSession);
+    }
+}