Update compound theme colors (#718)

* Update `*surfaceVariant` colors in `MaterialTheme`.

* Update screenshots

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Co-authored-by: ElementBot <benoitm+elementbot@element.io>

libraries/theme/src/main/kotlin/io/element/android/libraries/theme/MaterialThemeColors.kt

@@ -43,8 +43,8 @@ internal val materialColorSchemeLight = lightColorScheme(
     onBackground = LightDesignTokens.colorGray1400,
     surface = LightDesignTokens.colorThemeBg,
     onSurface = LightDesignTokens.colorGray1400,
-    surfaceVariant = LightDesignTokens.colorGray400,
-    onSurfaceVariant = LightDesignTokens.colorGray1400,
+    surfaceVariant = LightDesignTokens.colorGray300,
+    onSurfaceVariant = LightDesignTokens.colorGray900,
     surfaceTint = LightDesignTokens.colorGray1000,
     inverseSurface = LightDesignTokens.colorGray1300,
     inverseOnSurface = LightDesignTokens.colorThemeBg,
@@ -75,8 +75,8 @@ internal val materialColorSchemeDark = darkColorScheme(
     onBackground = DarkDesignTokens.colorGray1400,
     surface = DarkDesignTokens.colorThemeBg,
     onSurface = DarkDesignTokens.colorGray1400,
-    surfaceVariant = DarkDesignTokens.colorGray400,
-    onSurfaceVariant = DarkDesignTokens.colorGray1400,
+    surfaceVariant = DarkDesignTokens.colorGray300,
+    onSurfaceVariant = DarkDesignTokens.colorGray900,
     surfaceTint = DarkDesignTokens.colorGray1000,
     inverseSurface = DarkDesignTokens.colorGray1300,
     inverseOnSurface = DarkDesignTokens.colorThemeBg,