Update svg2ttf for xmldom vulnerability

[neotsn]

Hello everyone,

Over on xmldom the maintainers have had a hard time getting their package updated to address a security vulnerability, and have had to change where they publish on npm (not published as @xmldom/xmldom, see xmldom/xmldom#271).

This in turn triggered an update to svg2ttf that was just published as v6.0.3 (see fontello/svg2ttf#118).

Can we get this update added to this repository to address the security vulnerability and remove this now deprecated xmldom package?

Thanks for everything you do here.

Edit: wording.