Keep reference to CBL2CAPChannel so the system doesn't close it

Author: bgomberg

Sources/CombineCoreBluetooth/Models/L2CAPChannel.swift

@@ -1,6 +1,9 @@
 import Foundation
+import CoreBluetooth
 
 public struct L2CAPChannel {
+  // Need to keep a reference to this so the system doesn't close the channel
+  let rawValue: CBL2CAPChannel
   public let peer: Peer
   public let inputStream: InputStream
   public let outputStream: OutputStream
@@ -19,6 +22,7 @@ extension L2CAPChannel {
     }
 
     self.init(
+      rawValue: channel,
       peer: peer,
       inputStream: channel.inputStream,
       outputStream: channel.outputStream,