Update server packageset: squid3 -> squid

[Andreas Hasenack]

Hi,

squid (src) (v4.x) landed in cosmic
(https://bugs.launchpad.net/ubuntu/+source/squid3/+bug/1780944),
replacing squid3 (src). Could someone please update the server
packageset and include squid (without a version number next to its
name) in that set, as squid3 is there already?

The removal of squid3 (src) has been requested in
https://bugs.launchpad.net/ubuntu/+source/squid3/+bug/1793654

Please let me know if something else is needed, or if I emailed the wrong list.

Thanks!