[3.13] gh-124083: Skip test_signal.test_strsignal() on NetBSD (GH-124084) (#124223)

gh-124083: Skip test_signal.test_strsignal() on NetBSD (GH-124084)

Skip test_strsignal() on NetBSD due to TypeError.
(cherry picked from commit 36682c091407dc9c7e750c22fb71e62466952662)

Co-authored-by: Furkan Onder <furkanonder@protonmail.com>
Co-authored-by: T. Wouters <thomas@python.org>