ssh: update sshd_config(5) for RSA/SHA-1 signature removal

OpenSSH 8.8p1 removed RSA/SHA-1 signatures by default, but failed to
update sshd_config(5). It was updated upstream after the release in
b711bc01a7ec and da4035523406.

Fixes: 8c22023ca5e1 ("ssh: disable RSA/SHA-1 signatures")
Sponsored by: The FreeBSD Foundation