Php 8.4/8.5 support

[samrollin1]

Issue (warning):

Deprecated: Platformsh\ConfigReader\Config::__construct(): Implicitly marking parameter $environmentVariables as nullable is deprecated, the explicit nullable type must be used instead

Deprecated: Platformsh\ConfigReader\Config::getUpstreamRoutes(): Implicitly marking parameter $appName as nullable is deprecated, the explicit nullable type must be used instead

Solution:

config-reader/src/Config.php L#152

public function _construct(?array $environmentVariables = null, string $envPrefix = 'PLATFORM')...

config-reader/src/Config.php L#340

public function getUpstreamRoutes(?string $appName = null)...