wmt23 archive uses translator="refA"

[martinpopel]

unlike in previous years, where it used translator="A"
See any file in https://github.com/wmt-conference/wmt23-news-systems/tree/master/xml
versus e.g. https://github.com/wmt-conference/wmt22-news-systems/tree/master/xml

We have two options:

1. accept this PR
2. fix the wmt23-news-systems xml files (release v.0.1)

@kocmitom @mjpost @ozancaglayan what do you prefer?

[martinpopel]

OK, let's merge this PR now (as it fixes #261, i.e. there are users who need the fix). If someone (@kocmitom) publishes a new version (v.0.2) of wmt23-news-systems, it will be easy to change it back from refA to A (and the version from v.0.1 to v.0.2).