fix(subheader): change color to dark-L2

[Richard-lumapps]

CF-486

General summary

In order to fix insufficient contrast ratio with SubHeader component, changed color from dark-L3 to dark-L2.

Screenshots

using dark L3:

using dark L2:

StoryBook: https://b59d5881--5fbfb1d508c0520021560f10.chromatic.com/ (Chromatic build) ⚠️ Outdated commit

[FlorentDinet]

All good for me

[gcornut]

Can you modify the CHANGELOG.md in ## [Unreleased] > ### Changed?
I would suggest something like:

     - ListSubHeader: darken text color for better accessibility

[Richard-lumapps]

Can you modify the CHANGELOG.md in ## [Unreleased] > ### Changed? I would suggest something like:

     - ListSubHeader: darken text color for better accessibility

My bad, forgot to do this. This is done now.