Update to 5.504
    
    - New upstream release 5.504
      - Fix encoding of MIME parameters that contain a quoted string: "like \"this"
        (CPAN RT#80433)
      - Suppress useless warnings from tests (CPAN RT#80679)
      - Fix long-standing bug in encode_mimewords that can break multi-byte
        encodings such as UTF-8 (CPAN RT#5462)