Python 2 support has been removed in dunfell, and there is no obvious
requirement for python-curses in the demo images at this point, so just
remove python-curses from the packagegroup.
Bug-AGL: SPEC-3302
Signed-off-by: Scott Murray <scott.murray@konsulko.com>
Change-Id: I973315fb8273790840998ca3b03d7805cbc10a3b