Fix for 8.1.0beta2

[remicollet]

Deprecated: Return type of SimpleKafkaClient\Metadata\Collection::current() should either be compatible with Iterator::current(): mixed, or the #[ReturnTypeWillChange] attribute should be used to temporarily suppress the notice in Unknown on line 0
Deprecated: Return type of SimpleKafkaClient\Metadata\Collection::next() should either be compatible with Iterator::next(): void, or the #[ReturnTypeWillChange] attribute should be used to temporarily suppress the notice in Unknown on line 0

Sadly, this make usage of PHP 8.1 mandatory to generate arginfo... :(
(still usable with older version, thanks to compact macro added)

[remicollet]

1st commit is only cleanup of local git snapshot
3rd commit is only to completeness of the archive, these files are really "sources", and part of the project

[nick-zh]

@remicollet wow, many thanks for the fix and the cleanup. I highly appreciate it 🙇