Update Base64 decoding method in Diagnostics ViewModel

Switch from `Base64Url.Decode` to `Base64Url.DecodeFromChars` for improved decoding logic in diagnostics processing.

Author: khalidabuhakmeh

IdentityServer/v7/AspNetIdentityPasskeys/IdentityServerAspNetIdentityPasskeys/Pages/Diagnostics/ViewModel.cs

@@ -1,9 +1,9 @@
 // Copyright (c) Duende Software. All rights reserved.
 // Licensed under the MIT License. See LICENSE in the project root for license information.
 
+using System.Buffers.Text;
 using System.Text;
 using System.Text.Json;
-using Duende.IdentityModel;
 using Microsoft.AspNetCore.Authentication;
 
 namespace IdentityServerAspNetIdentityPasskeys.Pages.Diagnostics;
@@ -18,7 +18,7 @@ public ViewModel(AuthenticateResult result)
         {
             if (encoded != null)
             {
-                var bytes = Base64Url.Decode(encoded);
+                var bytes = Base64Url.DecodeFromChars(encoded);
                 var value = Encoding.UTF8.GetString(bytes);
                 Clients = JsonSerializer.Deserialize<string[]>(value) ?? Enumerable.Empty<string>();
                 return;