[RDY] Update bundled lua client version

The new version fixes defunct processes which causes random test failures on some systems(#1519)
Maybe change this to https://raw.githubusercontent.com/neovim/lua-client/0aefb79d8f60fd180594f376d20144414e1f37a4/nvim-client-0.0.1-3.rockspec? That way builds won't break between a lua-client version update and a neovim PR such as this one (see #1548).