please update SimpleSAMLphp/xmlseclibs

[Joern Clausen]

When connecting Mahara to a SAML IdP, parsing of attributes fails with an error. The reason is a bug in

auth/saml/extlib/simplesamlphp/vendor/robrichards/xmlseclibs/src/Utils/XPath.php

that has been fixed in SimpleSAMLphp 1.17.6:

--- XPath.php 2019/09/26 09:31:55 1.1
+++ XPath.php 2019/09/26 09:32:10
@@ -7,7 +7,7 @@
     const ALPHANUMERIC = '\w\d';
     const NUMERIC = '\d';
     const LETTERS = '\w';
- const EXTENDED_ALPHANUMERIC = '\w\d\s-_:\.';
+ const EXTENDED_ALPHANUMERIC = '\w\d\s\-_:\.';

     const SINGLE_QUOTE = '\'';
     const DOUBLE_QUOTE = '"';