Partially fixes issue #3256 by updating SASS syntax in main SCSS files.
To fully address the issue, FontAwesome should be updated to `v7.x` and
Tabler to `v3.30` or higher (see Tabler fix
[here](https://github.com/tabler/tabler-icons/pull/1256)), where the
SCSS has been fixed.
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Signed-off-by: George Araújo <george.gcac@gmail.com>
Co-authored-by: George Araújo <george.gcac@gmail.com>
