PHP 8.2 is supposed to deprecate the use of `['self', 'functionname']` for callables, suggesting the use of `[self::class, 'functionname']` instead. We made this change in a recent PR, and, while I'm thinking about it, I'll fix the remaining 2 modules with this construction. Vlookup is already adequately covered in unit tests. Reader/Xls/MD5 is not; a unit test is added.
oleibman