libncursesw5 for legacy linux support such as ubuntu 18.04

[rstm-sf]

Hello!

libncursesw5 for legacy linux support such as ubuntu 18.04. For versions starting from 20.04, version libncursesw6 is supplied by default. libncursesw5 can be installed separately

Maybe we should indicate in the readme that it needs to be installed separately? It seems to me that it is too early to bump version, since 18.04 will be supported for a long time

See also https://pkgs.org/download/libncursesw5 and https://github.com/ForNeVeR/Fenrir/issues/48