Correct variable arg to is_hidden

Author: mdeweerd

codespell_lib/_codespell.py

@@ -1153,7 +1153,7 @@ def build_file_list_with_os_walk(
     all_files = []
     for filename in files:
         # ignore hidden files
-        if is_hidden(root, check_hidden):
+        if is_hidden(filename, check_hidden):
             continue
         if os.path.isdir(filename):
             for root, dirs, dirfiles in os.walk(filename):