Log Message:
msmtp: update to 1.8.28. Changes:

- Build with libgsasl by default again (if found).
- Detect SMTPUTF8 server capability and use it if available.
- Add IDN support to --configure (build with libidn2 to enable this).
- Add special value 'none' to logfile_time_format to suppress time output.
- Add a testing infrastructure ('make check')
- Many improvements in the msmtpq script
- Many improvements to the vim scripts
- Add support for SCRAM-SHA-256-PLUS and SCRAM-SHA-1-PLUS authentication, and
  prefer SCRAM methods over the PLAIN method because of their superior
  properties.
- With --read-envelope-from, a Resent-From header is now used if it is present
  and appears before any From header
- Added a new configuration command 'from_full_name' to set a full name for the
  From header (like -F on the command line)
- Fixed the allow_from_override command

Packaging adjusted to more closely resemble mpop. Build-tested on NetBSD
and macOS.