Deprecation warnings for upcoming breaking changes in Sass

[JaroCamphuijsen]

As of sass 1.80 the @import statement (still used in css/theme/template/theme.scss) will be deprecated alongside with several other changes. WIth the current version specification in the package.json I got several deprecation warnings when using reveal.js.

Would be good to get reveal.js ready for sass 1.80, or for the moment pin the version at a lower minor version.

Would be good to check for all breaking changes in Sass.

[JaroCamphuijsen]

I'm happy to help, will try to open a PR in the coming weeks.

[hakimel]

Thanks but I've upgraded sass and fixed all deprecation warnings in the feature/vite branch. It's part of an all new build system for reveal.js 6.0.