Update simplesamlphp/saml2 requirement

Updates the requirements on [simplesamlphp/saml2](https://github.com/simplesamlphp/saml2) to permit the latest version.

Updates `simplesamlphp/saml2` to 5.0.0
- [Release notes](https://github.com/simplesamlphp/saml2/releases)
- [Commits](simplesamlphp/saml2@v4.6.0...v5.0.0)

---
updated-dependencies:
- dependency-name: simplesamlphp/saml2
  dependency-version: 5.0.0
  dependency-type: direct:production
  dependency-group: production-dependencies
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

composer.json

@@ -35,7 +35,7 @@
     },
     "require": {
         "php": "^8.1",
-        "simplesamlphp/saml2": "^4.6",
+        "simplesamlphp/saml2": "^5.0",
         "simplesamlphp/simplesamlphp": "^2.1",
         "symfony/http-foundation": "^6.4"
     },