upgrade openssh-server package from v9.5_p1-r0 to v9.6_p1-r0

https://web.archive.org/web/20231223082221/https://www.openssh.com/releasenotes.html
https://git.alpinelinux.org/aports/commit/main/openssh?h=3.19-stable&id=f73f84785693bbb1905ee679a50917e8bd1e44da

Dockerfile

@@ -5,7 +5,7 @@ FROM docker.io/alpine:3.19.0
 ARG BORGBACKUP_PACKAGE_VERSION=1.2.7-r0
 # https://www.openssh.com/releasenotes.html
 # https://git.alpinelinux.org/aports/log/main/openssh?h=3.19-stable
-ARG OPENSSH_SERVER_PACKAGE_VERSION=9.5_p1-r0
+ARG OPENSSH_SERVER_PACKAGE_VERSION=9.6_p1-r0
 # https://git.alpinelinux.org/aports/log/community/tini?h=3.19-stable
 ARG TINI_PACKAGE_VERSION=0.19.0-r2
 ARG USER=borg