community/notcurses: upgrade to 2.2.3

Upgrades 2.2.2 to 2.2.3. Restores unit tests. The failures we saw with 2.2.1 were very strange, and have proven unreproducible on my local Alpine setup. Hoping that they were an aberration, but am unsure -- if this breaks, and clogs up your autobuilders, please let me know; if you can get a coredump or valgrind output, I'll definitely be able to fix them. Please do not merge until the local build has succeeded. Thanks!