package/openssh: security bump to version 8.4p1

package/openssh: security bump to version 8.4p1

Fixes CVE-2020-15778: scp in OpenSSH through 8.3p1 allows command injection in
the scp.c toremote function, as demonstrated by backtick characters in the
destination argument. NOTE: the vendor reportedly has stated that they
intentionally omit validation of "anomalous argument transfers" because that
could "stand a great chance of breaking existing workflows."

https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-15778

Signed-off-by: Christian Stewart <christian@paral.in>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>