message: doc: add missing copyright header to getuniquepath.cpp
  This was missed in
diff: +// Copyright (c) 2021 The Bitcoin Core developers
  +// Distributed under the MIT software license, see the accompanying
  +// file COPYING or http://www.opensource.org/licenses/mit-license.php.
  +
  #include <random.h>
  #include <fs.h>
  #include <util/strencodings.h>
  