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)