[3.10] bpo-44446: support lineno being None in traceback.FrameSummary (GH-26781) (GH-27072)

As of 088a15c49d99ecb4c3bef93f8f40dd513c6cae3b, lineno is None instead
of -1 if there is no line number.

Signed-off-by: Filipe Laíns <lains@riseup.net>.
(cherry picked from commit 91a8f8c16ca9a7e2466a8241d9b41769ef97d094)

Co-authored-by: Filipe Laíns <lains@riseup.net>

Co-authored-by: Filipe Laíns <lains@riseup.net>