Fix SocketTransfer build

Author: tfpauly

Sources/SwiftNetwork/Connection/Connection.swift

@@ -969,7 +969,7 @@ public struct TCP: StreamProtocol {
 #if !NETWORK_EMBEDDED
 @_spi(Essentials)
 @available(Network 0.1.0, *)
-public struct DatagramBridge: DatagramProtocol {
+public struct DatagramBridge: DatagramProtocol, Sendable {
     public typealias ContentType = Void
 
     public let belowProtocol: Void
@@ -1353,7 +1353,7 @@ public struct QUICStream: StreamProtocol {
 /// UDP supports sending and receiving datagrams.
 @_spi(Essentials)
 @available(Network 0.1.0, *)
-public struct UDP: DatagramProtocol {
+public struct UDP: DatagramProtocol, Sendable {
     public typealias ContentType = [UInt8]
 
     private var preferNoChecksum: Bool?
@@ -1397,8 +1397,8 @@ public struct UDP: DatagramProtocol {
 /// protocol stack when configuring IP options.
 @_spi(Essentials)
 @available(Network 0.1.0, *)
-public struct IP: NetworkProtocolOptions {
-    public enum BelowProtocol {
+public struct IP: NetworkProtocolOptions, Sendable {
+    public enum BelowProtocol: Sendable {
         case void
         #if !NETWORK_EMBEDDED
         case bridge(DatagramBridge)

Sources/SwiftNetwork/Protocols/IPProtocol.swift

@@ -55,7 +55,7 @@ public struct IPProtocol: NetworkProtocol {
         // Destination Address: UInt128
     }
 
-    public enum Version: UInt8 {
+    public enum Version: UInt8, Sendable {
         /// Allows any IP version.
         case any = 0
         /// Uses only IP version 4 (IPv4).
@@ -64,7 +64,7 @@ public struct IPProtocol: NetworkProtocol {
         case v6 = 6
     }
 
-    public enum AddressPreference: UInt8 {
+    public enum AddressPreference: UInt8, Sendable {
         case any = 0
         case temporary = 1
         case stable = 2