bump data-values/serialization to 1.2.3 in the mediawiki-vendor repo
$ cat ./extensions/*/composer.json | grep data-values/serialization "data-values/serialization": "^1.2.1", "data-values/serialization": "^1.2.1",
https://github.com/DataValues/Serialization/compare/1.2.3...1.2.2