Gravatar: use WPDS neutral surface token for background (#53800)

Author: simison

projects/js-packages/components/changelog/gravatar-bg-color-token

@@ -0,0 +1,4 @@
+Significance: patch
+Type: changed
+
+Gravatar: Use the WordPress Design System neutral surface color token for the placeholder background.

projects/js-packages/components/components/gravatar/style.scss

@@ -1,5 +1,5 @@
 .jetpack-components-gravatar {
-	background-color: var(--jp-gray-5, #dcdcde);
+	background-color: var(--wpds-color-background-surface-neutral-strong);
 	border-radius: 50%;
 	display: block;
 	flex-shrink: 0; // Prevent shrinking when Gravatar is inside flex containers.