feat: add --color-text-on-muted variable to semantic color tokens

Author: sebousan

dist/css/semantic/color.css

@@ -70,6 +70,7 @@
     --color-text-on-dark: var(--color-white);
     --color-text-on-info: var(--color-white);
     --color-text-on-light: var(--color-gray-900);
+    --color-text-on-muted: var(--color-gray-900);
     --color-text-on-primary: var(--color-white);
     --color-text-on-secondary: var(--color-white);
     --color-text-on-success: var(--color-white);