Updated avatar background colors according to the most recent Design Toolkit

OfficeUIFabric/src/main/res/values/colors.xml

@@ -52,9 +52,8 @@
         <item>#C239B3</item>
         <item>#E3008C</item>
         <item>#603D30</item>
+        <item>#567C73</item>
         <item>#69797E</item>
-        <item>#7A7574</item>
-        <item>#393939</item>
     </array>
 
     <!--CalendarView-->