Add missing namespace

Author: tvdijen

src/Assert/HMACOutputLengthTrait.php

@@ -4,6 +4,7 @@
 
 namespace SimpleSAML\XMLSecurity\Assert;
 
+use SimpleSAML\Assert\AssertionFailedException;
 use SimpleSAML\XML\Exception\SchemaViolationException;
 use SimpleSAML\XMLSecurity\Exception\ProtocolViolationException;