Bump assert

Author: tvdijen

composer.json

@@ -39,7 +39,7 @@
         "ext-dom": "*",
 
         "robrichards/xmlseclibs": "^3.1.1",
-        "simplesamlphp/assert": "~0.2.2",
+        "simplesamlphp/assert": "~0.2.6",
         "simplesamlphp/xml-common": "^0.6.0"
     },
     "require-dev": {