Issue #3083877 by agami4: Update colors for the Sky theme

assets/css/brand--sky.css

assets/css/hero--sky.css

assets/css/preview.css

assets/css/teaser.css

color/color.inc

components/03-molecules/teaser/teaser.scss

components/04-organisms/hero/hero--sky.scss

components/brand--sky.scss

socialblue.libraries.yml

socialblue.theme