Raise supported version of SimpleSAMLphp to non-vulnerable version

Author: forevermatt

composer.json

@@ -13,7 +13,7 @@
   "require": {
     "php": ">=7.0",
     "simplesamlphp/composer-module-installer": "^1.1.5",
-    "simplesamlphp/simplesamlphp": "~1.17.7 || ~1.18.5",
+    "simplesamlphp/simplesamlphp": "~1.18.6",
     "silinternational/ssp-utilities": "^1.0"
   },
   "require-dev": {