[SideNavigation][a11y] contrast does not meet 3 to 1 ratio

[jenndiaz]

Description

The selected SideNav item color does not meet 3 to 1 contrast ratio with the adjacent background colors.

Steps to reproduce

1. Go to the docs site for side nav
2. Observe the selected standard variant, the background color of the selected variant compared to the background color of the adjacent SideNav items background colors

Expected behavior

The contrast between the non-selected and selected SideNav items MUST be at least 3:1.

Screenshots

Additional context

This is a failure of WCAG Success Criteria: 1.4.11 Non-text Contrast (Level AA) – WCAG 2.1
WCAG Understanding document: https://www.w3.org/WAI/WCAG21/Understanding/non-text-contrast