Extra newlines when using JoinVertical - Regression between v10 and v11

[kalensk]

Describe the bug
Extra newlines are added between every line appearing as if the text was double spaced when using lipgloss.JoinVertical(). It only appears to occur on subsequent renders/calls. This is a v11 regression as the issue does not occur appear v10.

Possibly related to #199

Setup
Please complete the following information along with version numbers, if applicable.

• OS [Ubuntu 22.04]
• Shell [Bash]
• Terminal Emulator: [None]
• Terminal Multiplexer [None]
• Locale [en_US.UTF-8]

To Reproduce
Steps to reproduce the behavior:

top := `I am top text
there is a lot in my header to show.`

middle := "I am in the middle with some bullets
- one
- two
- three"

bottom := "bottom text
with a fotter"

lipgloss.JoinVertical(lipgloss.Left, top, middle, bottom)

In v10 this example renders as expected, but in v11 it renders with double spacing which is unexpected and a bug.

The issue could be in github.com/charmbracelet/x/ansi with the switch from ansi.PrintableRuneWidth() to ansi.StringWidth()

Note the issue appears to only occurs on subsequent calls/renders, so I wonder if its a copy() related issue?