X icon instead of Twitter

[viharm]

Hi, I tried to replace the Twitter icon with the new X icon.

I used the icon from https://simpleicons.org/?q=x.

I then found two files where the SVG paths are defined.

/partials/icons/icons-symbol-defs.hbs & /src/svg-icons/symbol-defs.svg.

For an initial trial, I only changed the value of the SVG path. But I couldn't get it to align properly.

I'm happy to submit a merge request, but not sure what I'm doing wrong here.