dhcpcd: Update to 8.0.6

dhcpcd: Update to 8.0.6

For details see:
https://roy.marples.name/blog/dhcpcd-8-0-6-released

"inet6: Fix default route not being installed
DHCP: If root fs is network mounted, enable last lease extend
man: Fix lint errors.
BSD: avoid RTF_WASCLONED routes
DHCP: Give a better message when packet validation fails
DHCP: Ensure we have enough data to checksum IP and UDP

The last change fixes a potential DoS attack introduced in dhcpcd-8.0.3
when the checksuming code was changed to accomodate variable length
IP headers. The commit says since 7.2.0, but I've now decided that's not
the case."

Signed-off-by: Matthias Fischer <matthias.fischer@ipfire.org>
Signed-off-by: Arne Fitzenreiter <arne_f@ipfire.org>