Fix dir variable to remove trailing slash

Author: cywong-dev

Sprint-1/1-key-exercises/3-paths.js

@@ -17,7 +17,7 @@ console.log(`The base part of ${filePath} is ${base}`);
 // Create a variable to store the dir part of the filePath variable
 // Create a variable to store the ext part of the variable
 
-const dir = filePath.substring(0, filePath.lastIndexOf("/") + 1);;
+const dir = filePath.substring(0, filePath.lastIndexOf("/"));;
 const ext = filePath.substring(filePath.lastIndexOf('.') + 1);
 
 // https://www.google.com/search?q=slice+mdn