Copyright footer must be updated

The footer in the UI must be updated with the current year, now we have the following:

Copyright© 2010-2020

And we should update it to:

Copyright© 2010-2024{}

The resource bundle is located here:

https://github.com/apache/manifoldcf/tree/trunk/framework/ui-core/src/main/native2ascii/org/apache/manifoldcf/ui/i18n