tests/pkd: Fix OpenSSH version check
When running in FIPS mode, the OpenSSH version is not the first string
printed by "ssh -V". This makes the parser to find the first occurrence
of the version ignoring anything printed before it.
Signed-off-by: Anderson Toshiyuki Sasaki <firstname.lastname@example.org>
Reviewed-by: Andreas Schneider <email@example.com>