refined nick matching patter. word boundry (\b) doesn’t match on words ending in a boundry

fixes #3249

src/main/java/eu/siacs/conversations/services/NotificationService.java

@@ -98,7 +98,7 @@ public class NotificationService {
     }
 
     public static Pattern generateNickHighlightPattern(final String nick) {
-        return Pattern.compile("(?<=(^|\\s))" + Pattern.quote(nick) + "\\b");
+        return Pattern.compile("(?<=(^|\\s))" + Pattern.quote(nick) + "(?=\\s|$|\\p{Punct})");
     }
 
     @RequiresApi(api = Build.VERSION_CODES.O)