removing the column separator replaces with a space instead of removing it altogether.

```racket
> (print-table '((a b) (c d)))
┌─┬─┐
│a│b│
├─┼─┤
│c│d│
└─┴─┘
> (print-table '((a b) (c d)) #:col-sep? #f)
┌───┐
│a b│
├───┤
│c d│
└───┘
> (print-table '((a b) (c d)) #:row-sep? #f)
┌─┬─┐
│a│b│
│c│d│
└─┴─┘
```
Expected behaviour:
```
> (print-table '((a b)) #:col-sep? '(#f))
┌──┐
│ab│
└──┘
```
just like removing the row-sep removes the line.