[HttpClient] Deprecate using amphp/http-client < 5

[nicolas-grekas]

Q	A
Feature PR	symfony/symfony#60704
PR author(s)	@nicolas-grekas
Merged in	7.4

We created this issue to not forget to document this new feature. We would really appreciate if you can help us with this task. If you are not sure how to do it, please ask us and we will help you.

To fix this issue, please create a PR against the 7.4 branch in the symfony-docs repository.

Thank you! 😃

[stof]

I found a reference to the amphp/http-client version number in https://symfony.com/doc/current/http_client.html#enabling-curl-support
as this is a reference about the min version supporting HTTP/2, I think we only need to update the doc in the 8.0 branch where support for version 4.2 is dropped.

[javiereguiluz]

I like your plan @stof, so I did that in #21063.