Translation files for the layout domain is stale

## What Happened

Translation files for `layout` domain seems to be old; For example, the copyright in the footer now uses a variable to represent a year:

https://github.com/elementary/website/blob/master/_templates/footer.php#L6

However, the counterpart string in weblate uses a fixed year "2017":

https://l10n.elementary.io/translate/website/layout/nn/?checksum=3ab5aca5da360364&sort_by=-priority,position

See also the discussion in the link above.

## Expected Behavior

The translation files for `layout` domain should be up-to-date. And thus, the year in the copyright should use a variable like `%{year}`

## Steps to Reproduce

1. See the source string on GitHub: https://github.com/elementary/website/blob/master/_templates/footer.php#L6
2. See the translation string on Weblate is stale: https://l10n.elementary.io/translate/website/layout/nn/?checksum=3ab5aca5da360364&sort_by=-priority,position

### Logs

N/A

## Platform Information

Not platform dependance