Embedded HTML with double quoted attributes breaks interpreter

[robacarp]

This template:

            div
              <img src="/">

Causes this compile time error:

Syntax error in expanded macro: macro_4629572560:239: unexpected token: DELIMITER_START

__kilt_io__ << ("<img src="/">").to_s(__kilt_io__)
                           ^

The " symbol isn't being escaped, and it's causing an error in the string literal.

A quick workaround for this is to use single quotes.

slang 1.7.1
crystal 0.24.2