Admin: Improve Dashboard icon contrast.

The icons used across the dashboard had too low contrast to pass AA WCAG guidelines. They’re now slightly darker for better contrast.

Props @melchoyce, @SergeyBiryukov, @chetan200891 , @kjellr 
Fixes #46935


git-svn-id: https://develop.svn.wordpress.org/trunk@45700 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-admin/css/dashboard.css

@@ -220,7 +220,7 @@
 .welcome-panel .welcome-icon:before,
 #dashboard_right_now li a:before,
 #dashboard_right_now li span:before {
-	color: #82878c;
+	color: #606a73;
 	font: normal 20px/1 dashicons;
 	speak: none;
 	display: inline-block;
@@ -422,7 +422,7 @@
 }
 
 .event-icon:before {
-	color: #82878C;
+	color: #606a73;
 	font-size: 18px;
 }
 .event-meetup .event-icon:before {