Set color-hex-case to null

There is both lowercase and uppercase in some files so this should just make life easier if someone is using a stylelinter

Signed-off-by: Šimon Brandner <simon.bra.ag@gmail.com>

.stylelintrc.js

@@ -4,6 +4,7 @@ module.exports = {
         "stylelint-scss",
     ],
     "rules": {
+        "color-hex-case": null,
         "indentation": 4,
         "comment-empty-line-before": null,
         "declaration-empty-line-before": null,