g_new_file_for_path() throws too many open files error after a while

This fix calls the unref() function on the file object, when the extension get disbled.
Free file resources after usage
Fix: too many open files error

After a while Gnome gives a "Gio.IOErrorEnum: Too many open files" error during a file operation.
This fix closes the GFileEnumerator input stream when it no longer needed.