Remove virtual from ToBytes method (Azure#34045)

Author: JoshLove-msft

sdk/core/Azure.Core.Amqp/api/Azure.Core.Amqp.netstandard2.0.cs

@@ -28,7 +28,7 @@ public AmqpAnnotatedMessage(Azure.Core.Amqp.AmqpMessageBody body) { }
         public Azure.Core.Amqp.AmqpMessageProperties Properties { get { throw null; } }
         public static Azure.Core.Amqp.AmqpAnnotatedMessage FromBytes(System.BinaryData messageBytes) { throw null; }
         public bool HasSection(Azure.Core.Amqp.AmqpMessageSection section) { throw null; }
-        public virtual System.BinaryData ToBytes() { throw null; }
+        public System.BinaryData ToBytes() { throw null; }
     }
     public partial class AmqpMessageBody
     {

sdk/core/Azure.Core.Amqp/src/AmqpAnnotatedMessage.cs

@@ -161,7 +161,7 @@ public bool HasSection(AmqpMessageSection section) =>
         /// <seealso href="http://docs.oasis-open.org/amqp/core/v1.0/os/amqp-core-messaging-v1.0-os.html#section-message-format"/>
         /// </summary>
         /// <returns>A <see cref="BinaryData"/> instance representing the serialized message.</returns>
-        public virtual BinaryData ToBytes()
+        public BinaryData ToBytes()
         {
             var stream = AmqpAnnotatedMessageConverter.ToAmqpMessage(this).ToStream();
             return BinaryData.FromStream(stream);