mono6 conflicts with chicken 5

[Nikita Gillmann <nikita%NetBSD.org@localhost>]

Hi,

can we CONFLICTS and/or move/patch either of chicken or mono6 to not
result in this conflict?

To myself this is a bug, but my checkout is lagging behind a bit the
last couple of months.

---Jul 23 21:28:15: installing mono-6.8.0.105nb5...
pkg_add: Conflicting PLIST with chicken-5.2.0: bin/csc