Serialized certificates loaded as X509Certificate2

Instances of X509Certificate2 passed into an MqttClientOptionsBuilder lose data and functionality by being loaded as an X509Certificate.

Frameworks/MQTTnet.NetStandard/Implementations/MqttTcpChannel.cs

@@ -130,7 +130,7 @@ namespace MQTTnet.Implementations
 
             foreach (var certificate in options.TlsOptions.Certificates)
             {
-                certificates.Add(new X509Certificate(certificate));
+                certificates.Add(new X509Certificate2(certificate));
             }
 
             return certificates;
@@ -155,4 +155,4 @@ namespace MQTTnet.Implementations
 
     }
 }
-#endif
+#endif