Whitespace is removed around <tspan> elements

[Rich-Harris]

Describe the bug
The whitespace between foo and bar is removed:

<svg>
  <text>
    <tspan>foo</tspan> {"bar"}
  </text>
</svg>

To Reproduce
https://svelte.dev/repl/c80264cf1a924890bf1e23374337b141?version=3.15.0

Expected behavior
Both <text> elements should contain foo bar, not foobar.

Severity
Can be worked around, but is a bit of a nuisance

I have a fix for this... PR on its way :)

[Conduitry]

Fixed in 3.16.6.