How to fix a Swift 6 warning: "Sending main actor-isolated value of type 'WebAuthenticationSession' with later accesses to nonisolated context risks causing data races; this is an error in the Swift 6 language mode"

ContentView.swift

// https://iosdev.space/@andy/112714337582288785

import AuthenticationServices
import SwiftUI

struct ContentView: View {
    @State var url = URL(string: "https://example.net")!

    @Environment(\.webAuthenticationSession) var webAuthenticationSession

    var body: some View {
        VStack {
            Button {
                let session = webAuthenticationSession // copy before entering an isolated context
                Task {
                    let token = try await session.authenticate(
                        using: url,
                        callback: .https(host: "example.net", path: "/whatever"),
                        preferredBrowserSession: nil,
                        additionalHeaderFields: [:]
                    )
                    print("token: \(token)")
                }
            } label: {
                Text("Authenticate")
            }
        }
        .padding()
    }
}