Support iterm2 through ueberzugpp

[Yongwoo Lee]

It seems like iterm2 over SSH is not working even with ueberzugpp ( I did not test it in local, but it would not work well )

I fixed the problem by changing two lines in ueberzug.lua
This fix works in tmux over SSH.

  6 M lua/image/backends/ueberzug.lua
  7 @@ -5,12 +5,12 @@ local should_be_alive = false
  8
  9  local spawn = function()
 10    local stdin = vim.loop.new_pipe()
 11 -  local stdout = vim.loop.new_pipe()
 12 +  local stdout = vim.loop.new_tty(1, false)
 13    local stderr = vim.loop.new_pipe()
 14    should_be_alive = true
 15
 16    local handle, pid = vim.loop.spawn("ueberzug", {
 17 -    args = { "layer", "--silent" },
 18 +    args = { "layer", "--silent", "-o", "iterm2" },
 19      stdio = { stdin, stdout, stderr },
 20    }, function(code, signal)
 21      child = nil
 

I did not test it well, leaving this as an issue.