Return type of ClickHouseDB\Statement::current() should either be compatible with Iterator::current()

[m1khal3v]

Fix deprecations

2022-06-21T20:09:15+00:00 [info] Deprecated: Return type of ClickHouseDB\Statement::current() should either be compatible with Iterator::current(): mixed, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice
2022-06-21T20:09:15+00:00 [info] User Deprecated: Method "Iterator::current()" might add "mixed" as a native return type declaration in the future. Do the same in implementation "ClickHouseDB\Statement" now to avoid errors or add an explicit @return annotation to suppress this message.

[isublimity]

Thx!