Administration: Update default fallback color for SVG icons.

Currently, when an SVG is used as a menu icon, the color is inconsistent with the other, default dashicons and the contrast ratio does not meet the minimum requirement for accessibility.

This updates the base color for the default `fresh` color scheme to ensure consistency and proper contrast.

Props swift, dschalk.
Fixes #44209.

git-svn-id: https://develop.svn.wordpress.org/trunk@44353 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-admin/includes/misc.php

@@ -925,7 +925,7 @@ function wp_color_scheme_settings() {
 	} else {
 		// Fall back to the default set of icon colors if the default scheme is missing.
 		$icon_colors = array(
-			'base'    => '#82878c',
+			'base'    => '#a0a5aa',
 			'focus'   => '#00a0d2',
 			'current' => '#fff',
 		);

src/wp-includes/general-template.php

@@ -4043,7 +4043,7 @@ function register_admin_color_schemes() {
 		false,
 		array( '#222', '#333', '#0073aa', '#00a0d2' ),
 		array(
-			'base'    => '#82878c',
+			'base'    => '#a0a5aa',
 			'focus'   => '#00a0d2',
 			'current' => '#fff',
 		)