Enforce at least test-framework 1.11.5

Author: tvdijen

composer.json

@@ -49,7 +49,7 @@
         "simplesamlphp/composer-xmlprovider-installer": "~1.3"
     },
     "require-dev": {
-        "simplesamlphp/simplesamlphp-test-framework": "~1.11"
+        "simplesamlphp/simplesamlphp-test-framework": "~1.11.5"
     },
     "support": {
         "issues": "https://github.com/simplesamlphp/xml-common/issues",