ovn-vif ci: the CI pipeline fails due to too old scapy

[Frode Nordahl]

The upstream OVN VIF CI pipeline currently fails due to a too old version of scapy.

This condition is visible in the "dns lookup : EDNS" test and the following hint is provided in the scapy.log:
2024-03-04T07:31:01.779Z | 0 | scapy-server | INFO | scapy server ready
2024-03-04T07:31:01.911Z | 3 | scapy-server | INFO | received payload request: Ether(dst='00:00:00:00:00:02', src='00:00:00:00:00:01') / IP(dst='10.0.0.254', src='10.0.0.1') / UDP(sport=42424, dport=53) / DNS(rd=1, qd=DNSQR(qname='foo.ovn.org'), arcount=1, ar= DNSRR(type='OPT', rclass=4096, rdata=EDNS0ClientSubnet(source_plen=24, address='10.0.0.1')))
2024-03-04T07:31:01.913Z | 4 | scapy-server | ERR | failed to process payload request: name 'EDNS0ClientSubnet' is not defined
Traceback (most recent call last):
  File "/home/ubuntu/src/ovn-vif/ovn/tests/testsuite.dir/159/../../../tests/scapy-server.py", line 32, in process
    return binascii.hexlify(raw(eval(data))).decode()
  File "<string>", line 1, in <module>
NameError: name 'EDNS0ClientSubnet' is not defined

This test works for the upstream OVN CI because they are running the testsuite inside a container based on the latest Ubuntu version [0].

We need to do something similar for the OVN VIF CI.

0: https://github.com/ovn-org/ovn/blob/main/utilities/containers/ubuntu/Dockerfile