fix: fix type hints for delete_existing_files() (#96)

src/rapids_dependency_file_generator/_rapids_dependency_file_generator.py

@@ -18,15 +18,15 @@
 HEADER = f"# This file is generated by `{cli_name}`."
 
 
-def delete_existing_files(root: os.PathLike) -> None:
+def delete_existing_files(root: str) -> None:
     """Delete any files generated by this generator.
 
     This function can be used to clean up a directory tree before generating a new set
     of files from scratch.
 
     Parameters
     ----------
-    root : PathLike
+    root : str
         The path (relative or absolute) to the root of the directory tree to search for files to delete.
     """
     for dirpath, _, filenames in os.walk(root):