[Maintainer update] shells/scponly: Update to 4.3.

Update to 4.3. Highlights in this release,

• Compatibility of WinSCP in SCP mode improved.
• The scponlyc (chroot'ed version of scponly) works again.

PR: ports/91039
Submitted by: Hideyuki KURASHINA <rushani@FreeBSD.org>