session_spec.lua: skip ECONNREFUSED test
session_spec.lua: skip ECONNREFUSED test

see https://github.com/luvit/luv/pull/350
see https://github.com/luvit/luv/issues/433#issuecomment-551163759
see https://github.com/neovim/lua-client/pull/50#issuecomment-583782367

neovim/lua-client,neovim/lua-client,neovim/lua-client