Update dependencies, use Laminas Diactoros, ~update signature for Encoder::_doRequest and Decoder::_doRequest~

[kiike]

First, thank you so much for ReactPHP and ReactPHP-Soap! I am using both in a small project and bring a very nice improvement in performance.

I noticed that:

• the dependencies for this project are a bit old. For instance, the blocking library is deprectaed in favour or React/Async
• plus there's an undocumented dependency on the RingCentral's PSR7 library

I went ahead and tried to address these observations:

• updating dependencies,
• moving from RingCentral's PSR7 library to Laminas Diactoros, which is maintained at the moment
• moved from usage of '\Clue\React\Block' to 'Async\Await'

Looking forward to your feedback!

EDIT: Since promises aims to support older PHP versions, I am dropping the _doRequest signature update to not break compatibility with PHP<8.0