[clap_complete] Missing newline character for zsh completion at the end

[xylous]

Please complete the following tasks

• I have searched the discussions
• I have searched the existing issues

Rust Version

rustc 1.57.0 (Arch Linux rust 1:1.57.0-1)

Clap Version

3.0.5

Minimal reproducible code

use clap::App;
use clap_complete::{generate, shells::Zsh};
use std::io;

fn main() {
    let mut app = App::new("myapp")
        .subcommand(App::new("test").subcommand(App::new("config")))
        .subcommand(App::new("hello"));

    generate(Zsh, &mut app, "myapp", &mut io::stdout());
}

Steps to reproduce the bug with the above code

cargo run

Actual Behaviour

When the command is ran, there's no newline character at the end of the output

Expected Behaviour

There should be a newline character at the end of the output, like how there is on all other completions' outputs

Additional Context

No response

Debug Output

No response

[xylous]

I created a pull request to solve this issue, #3275

To be fair, it isn't hard to solve.