Use printf instead of w in PTY test for easier cross-platform support

flake.nix

@@ -24,7 +24,6 @@
 
         testDeps = with pkgs; [
           python3
-          procps  # provides `w` binary
         ];
 
         mkDevShell = rust: pkgs.mkShell {

src/pty.rs

@@ -520,7 +520,7 @@ sys.stdout.write('bar');
         let mut recorder = TestRecorder::default();
 
         super::exec(
-            &["w"],
+            &["printf", "hello world\n"],
             &ExtraEnv::new(),
             &mut NullTty::open().unwrap(),
             None,