Example needs update for Spring 7

[ML-Marco]

    @Bean
    public SecurityFilterChain filterChain(HttpSecurity http, AuthenticationManager authenticationManager) throws Exception {
        // WebAuthn Login
        http.apply(WebAuthnLoginConfigurer.webAuthnLogin())
            .loginPage("/login")
        // snip

This no longer works because it doesn't set the securityBuilder in the configurer. It needs to be updated to:

    @Bean
    public SecurityFilterChain filterChain(HttpSecurity http, AuthenticationManager authenticationManager) throws Exception {
        // WebAuthn Login
        http.with(WebAuthnLoginConfigurer.webAuthnLogin(), customizer -> customizer
            .loginPage("/login"));