Switch to using subprocess::shell (#1264)

* Switch to using `shell`

Switch to using the shell for subprocess to enable more natural shelling out.

* Update external.rs

* This is a test with .shell() for external

* El pollo loco's PR

* co co co

* Attempt to fix windows

* Fmt

* Less is more?

Co-authored-by: Andrés N. Robalino <andres@androbtech.com>

tests/shell/pipeline/commands/external.rs

@@ -17,7 +17,7 @@ fn shows_error_for_command_not_found() {
         "ferris_is_not_here.exe"
     );
 
-    assert!(actual.contains("Command not found"));
+    assert!(actual.contains("External command failed"));
 }
 
 mod it_evaluation {