chore: change default port of collab server (#7641)

.env.development

@@ -5,7 +5,7 @@ VITE_APP_LIBRARY_URL=https://libraries.excalidraw.com
 VITE_APP_LIBRARY_BACKEND=https://us-central1-excalidraw-room-persistence.cloudfunctions.net/libraries
 
 # collaboration WebSocket server (https://github.com/excalidraw/excalidraw-room)
-VITE_APP_WS_SERVER_URL=http://localhost:3020
+VITE_APP_WS_SERVER_URL=http://localhost:3002
 
 VITE_APP_PLUS_LP=https://plus.excalidraw.com
 VITE_APP_PLUS_APP=https://app.excalidraw.com