Change closed PR icon color from red to purple to match GitHub UI

Co-authored-by: alexr00 <38270282+alexr00@users.noreply.github.com>

Author: Copilot

package.json

@@ -3704,8 +3704,8 @@
 			{
 				"id": "pullRequests.closed",
 				"defaults": {
-					"dark": "#cb2431",
-					"light": "#cb2431",
+					"dark": "#8957e5",
+					"light": "#8957e5",
 					"highContrast": "editor.background",
 					"highContrastLight": "editor.background"
 				},