python3: add cgitb, zipapp ptest dependencies

Without these, test_cgitb and test_zipapp both fail when running the
python3 ptests.

Also reorder the ${PN}-misc list to be alphabetical.

Signed-off-by: Trevor Gamblin <tgamblin@baylibre.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>