stty panics when output is redirected

uutils coreutils 0.1.0, GNU coreutils 9.7, Arch Linux

```
$ /usr/bin/stty > out.txt
```
out.txt: 
```
speed 38400 baud; line = 0;
```

```
$ coreutils stty > out.txt

thread 'main' panicked at src/uu/stty/src/stty.rs:203:52:
Could not get terminal attributes: ENOTTY
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
```