Net::Frame::Simple has a long dependency chain, avoid porting, skip tests

Index: t/104-offer-o90-o120.t
--- t/104-offer-o90-o120.t.orig
+++ t/104-offer-o90-o120.t
@@ -6,11 +6,11 @@ use FindBin;
 
 use strict;
 
+use Test::Requires qw(Net::Frame::Simple);
+use Net::Frame::Dump::Offline;
+
 BEGIN { use_ok('Net::DHCP::Packet'); }
 BEGIN { use_ok('Net::DHCP::Constants'); }
-
-use Net::Frame::Simple;
-use Net::Frame::Dump::Offline;
 
 my %values = (
     htype => 1,
