refactoring: remove unnecessary internal keyword parameter

src/builtins/cd.rs

@@ -2,7 +2,7 @@ use std::env::set_current_dir;
 
 use crate::error::ShellError;
 
-pub fn run(keyword: &str, args: &[&str]) -> Result<(), ShellError> {
+pub fn run(args: &[&str]) -> Result<(), ShellError> {
     set_current_dir(args[0]);
     Ok(())
 }

src/builtins/mod.rs

@@ -9,7 +9,7 @@ pub fn is_builtin(keyword: &str) -> bool {
 
 pub fn execute_builtin(keyword: &str, args: &[&str]) -> Result<(), ShellError> {
     match keyword {
-        "cd" => cd::run(keyword, args)?,
+        "cd" => cd::run(args)?,
         _ => {}
     }
     Ok(())