fix(linux): don't separate arguments

Author: GreasySlug

crates/erg_common/python_util.rs

@@ -655,11 +655,7 @@ pub fn _opt_which_python() -> Result<String, String> {
             .arg("python")
             .output()
     } else {
-        Command::new("sh")
-            .arg("-c")
-            .arg("which")
-            .arg("python3")
-            .output()
+        Command::new("sh").arg("-c").arg("which python3").output()
     };
     let Ok(out) = out else {
         return Err(format!("{}: python not found", fn_name_full!()));