Show renderer is not escaping newlines for objects that are not string

[ronisbr]

struct MyObject end

Base.show(io::IO, ::MyObject) = print(io, "a\nb\nc")

julia> pretty_table([mo mo], renderer = :show)
┌────────┬────────┐
│ Col. 1 │ Col. 2 │
├────────┼────────┤
│    a
b
c │    a
b
c │
└────────┴────────┘