This release requires PHP 7.1 or later - APIs have not changed since 0.2.x, but static type-hints have been added, so you may need to add type-hints to custom implementations of any interfaces defined by this package.
Message::getDate() now returns DateTimeInterface - it previously returned a UNIX (integer) timestamp.
Message::setDate() still accepts UNIX timestamps and strings, and now also DateTime and DateTimeImmutable.