Design tokens v3.1.0

[ty2k]

This PR updates the @bcgov/design-tokens library to v3.1.0. This version of the code is currently published on npm on the next tag as v3.1.0-rc3.

Compared to v3.0.1, this version only contains additions:

# Changelog ## 3.1.0 ### Added - Comments added to tokens to document intended usage - `layout.padding.hair` added to match `layout.margin.hair` - New color tokens added: - `surface.color.primary.default` - `surface.color.primary.hover` - `surface.color.primary.pressed` - `surface.color.primary.disabled` - `surface.color.secondary.default` - `surface.color.secondary.hover` - `surface.color.secondary.pressed` - `surface.color.secondary.disabled` - `surface.color.tertiary.default` - `surface.color.tertiary.hover` - `surface.color.tertiary.pressed` - `surface.color.tertiary.disabled`

I've taken care to preserve the deprecated typography.fontWeights.italic token in c62947a906b1802ebf256828df7daf5730c8bbd4.

Once this PR is merged, I will publish v3.1.0 on npm on the latest tag.