[Config] Allow php85: true on withPhpSets()

[samsonasik]

Allow user to configure:

use Rector\ValueObject\PhpVersion;

->withPhpSets(php85: true)
->witPHPVersion(PhpVersion::PHP_85);

to test next php 8.5.

[samsonasik]

I added test to proof that this is working 8ab4683 👍

[samsonasik]

All checks have passed 🎉 @TomasVotruba I am merging it ;)

[github-actions]

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