SimpleSAMLphp v2.5.0 is due to be released later this month, timed with the Symfony 7.4 release. There have been two release candidates of SimpleSAMLphp 2.5.0 currently.

The explicit dependency in composer.json for https://github.com/cirrusidentity/simplesamlphp-module-authoauth2/blob/53f603e08a2f117515d02929a60a201f4386e293/composer.json#L19 will need to be updated to include 7.x. I suggest also dropping support for unsupported Symfony versions (prior to 5.4):

    "symfony/cache": "^7.0|^6.0|^5.4",