chore: prepare release 2.3.4

[phil-davis]

The changes are mostly CI and tooling.
There are small code-style changes that the later php-cs-fixer applied, so I may as well release what is there.
The code is confirmed in CI that it passes with PHP 8.4

[phil-davis]

phpstan is complaining. I suppose that there is a newer version that finds more things.
It passed 2 hours ago in PR #117 with phpstan 1.11.8

And now there is phpstan 1.12.0 that reports problems.

The cause is:
phpstan/phpstan-src@bd2cec1

"Precise type for $matches from preg_match generally available"

phpstan is now smarter and knows what keys are guaranteed to end up in $matches from a call to preg_match
And so it is complaining about some of our code that does unnecessary isset() checks.

For now, I think that I will leave the v2 code as it is (overly self-protective) and ignore the phpstan messages.

[phil-davis]

phpstan passes on PHP 7.4, but on PHP 8.4 it says:
https://github.com/sabre-io/uri/actions/runs/10577749388/job/29306396107?pr=120

------ ------------------------------------------------------------------ 
  Line   lib/functions.php                                                 
 ------ ------------------------------------------------------------------ 
  353    Strict comparison using === between false and string will always  
         evaluate to false.                                                
  372    Strict comparison using === between false and string will always  
         evaluate to false.                                                
 ------ ------------------------------------------------------------------ 

And that is correct. Since PHP 8.0 the substr function always returns a string.
But in PHP 7.4 it could return false

https://www.php.net/manual/en/function.substr.php

I will ignore that too. I don't want to add complexity by checking the PHP version before bothering with the === checks.