feature: newServer notification as normal

Reduce the notification state severity to normal.

There being a new version available is a pretty low severity
notification. Just the fact that there is a notification for
is probably enough.

See also SignalK/instrumentpanel#245

src/index.ts

@@ -375,7 +375,7 @@ class Server {
               {
                 path: 'notifications.server.newVersion',
                 value: {
-                  state: 'alert',
+                  state: 'normal',
                   method: [],
                   message: msg
                 }