Fix(web): Remove will-change from Modal to prevent high memory co…

…nsumption

Firefox warns about potential high memory consumption when `will-change`
is used on big areas. Therefore it seems better to remove it in this case to
free up the memory for smaller tweaks in Spirit and also for other performance
optimisations our users might want to make.

https://dev.opera.com/articles/css-will-change-property/

packages/web/src/scss/components/Modal/_Modal.scss

@@ -46,7 +46,6 @@
     @media (prefers-reduced-motion: no-preference) {
         transition-property: visibility, opacity;
         transition-duration: theme.$transition-duration;
-        will-change: visibility, opacity;
 
         // 2.
         &::before {