change raw.githubusercontent.com to raw.github.com

in the case of 'dhcphost=raw.githubusercontent.com/kotaro-dev/ubuntu-installer/critical'
need https://
like - sudo wget http://${dhcphost}/smb.conf -O /etc/samba/smb.conf
but the case as 'dhcphost=raw.github.com/kotaro-dev/ubuntu-installer/critical'
I cloud use http protocol
ok - sudo wget http://${dhcphost}/smb.conf -O /etc/samba/smb.conf