Fix cutoff last line when line_height is less than 1.0

Fixes #2502.

Sorry guys for the delay, but this should fix #2502.

It doesn't completely fix it for when markup is True with more than one line, but I don't think it's quite possible to to fix there as well without a lot more effort. The reason being that imagine for the various lines we use different `line_height`. Then to find the total required height so that nothing is cut off, we'd need to keep track of the various leftovers that doesn't fit vertically on each line to get the maximum total. Because keep in mind that `line_height` just moves lines rather than actually rescaling. But for markup, I imagine the user has the option to just use a smaller font size rather than changing the line size.