fix: skeleton not using theme variables (#9712)

Fix linked to this discord issue:
https://discord.com/channels/1130383047699738754/1329509340494692444

---------

Co-authored-by: Weiko <corentin@twenty.com>

packages/twenty-front/src/modules/activities/components/SkeletonLoader.tsx

@@ -42,6 +42,7 @@ export const SKELETON_LOADER_HEIGHT_SIZES = {
 
 const SkeletonColumnLoader = ({ height }: { height: number }) => {
   const theme = useTheme();
+
   return (
     <SkeletonTheme
       baseColor={theme.background.tertiary}