Update Composer dependencies

[kayjoosten]

Goal

Update outdated Composer dependencies (already on PHP 8.5, no runtime bump needed).

What needs to be done

• Run composer outdated --direct, update patch/minor releases
• Review major-version bumps case by case: cweagans/composer-patches (~2.0), doctrine/doctrine-bundle (~3.2), doctrine/doctrine-migrations-bundle (~4.0), simplesamlphp/assert (~3.0), simplesamlphp/saml2 (~6.2)
• composer/package-versions-deprecated is abandoned — evaluate removal
• Full test suite + static analysis green after update

[pmeulen]

As discussed: Make sub-tickets for sensible work units