cf T376276: PHP 8.4: Implicitly nullable parameter declarations deprecated

In T376276#10306963, @Umherirrender wrote:

Running the sniff from T362014 against mediawiki/vendor shows many code in different packages

• data-values/common - no issue found on github (https://github.com/DataValues/Common/issues)
• data-values/geo - no issue found on github (https://github.com/DataValues/Geo/issues)
• data-values/interfaces - no issue found on github (https://github.com/DataValues/Interfaces/issues)
• data-values/number - no issue found on github (https://github.com/wmde/Number/issues)
• data-values/time - no issue found on github (https://github.com/wmde/Time/issues)
• diff/diff - no issue found on github (https://github.com/wmde/Diff/issues)
• serialization/serialization - no issue found on github (https://github.com/wmde/Serialization/pulls)