Update BackgroundDark.ts (#8883)

Fixes #8877

Improved Contrast for better modal visibility

### After
![CleanShot 2024-12-05 at 09 39
59](https://github.com/user-attachments/assets/1a8723d3-fe2b-488f-9e45-7f396af0cbb4)

### Before
![CleanShot 2024-12-05 at 09 39
05](https://github.com/user-attachments/assets/b2882e37-265b-42db-8bed-d32e756cc737)

packages/twenty-ui/src/theme/constants/BackgroundDark.ts

@@ -24,9 +24,9 @@ export const BACKGROUND_DARK = {
     danger: RGBA(COLOR.red, 0.08),
     blue: RGBA(COLOR.blue, 0.2),
   },
-  overlayPrimary: RGBA(GRAY_SCALE.gray80, 0.8),
-  overlaySecondary: RGBA(GRAY_SCALE.gray80, 0.4),
-  overlayTertiary: RGBA(GRAY_SCALE.gray80, 0.4),
+  overlayPrimary: RGBA(GRAY_SCALE.gray100, 0.8),
+  overlaySecondary: RGBA(GRAY_SCALE.gray100, 0.6),
+  overlayTertiary: RGBA(GRAY_SCALE.gray100, 0.4),
   radialGradient: `radial-gradient(50% 62.62% at 50% 0%, #505050 0%, ${GRAY_SCALE.gray60} 100%)`,
   radialGradientHover: `radial-gradient(76.32% 95.59% at 50% 0%, #505050 0%, ${GRAY_SCALE.gray60} 100%)`,
   primaryInverted: GRAY_SCALE.gray20,