Update simplesamlphp/xml-common requirement (#63)

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

Updates `simplesamlphp/xml-common` to 1.25.0
- [Release notes](https://github.com/simplesamlphp/xml-common/releases)
- [Commits](simplesamlphp/xml-common@v1.24.0...v1.25.0)

---
updated-dependencies:
- dependency-name: simplesamlphp/xml-common
  dependency-version: 1.25.0
  dependency-type: direct:production
  dependency-group: production-dependencies
...

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Author: dependabot[bot]

composer.json

@@ -44,7 +44,7 @@
         "ext-spl": "*",
 
         "simplesamlphp/assert": "~1.8.0",
-        "simplesamlphp/xml-common": "~1.24.0"
+        "simplesamlphp/xml-common": "~1.25.0"
     },
     "require-dev": {
         "simplesamlphp/simplesamlphp-test-framework": "~1.9.1"