Remove test that doesn't really test anything

tests/lib/SimpleSAML/XML/Shib13/AuthnResponseTest.php

@@ -65,18 +65,6 @@ XML;
     }
 
 
-    /**
-     * @covers \SimpleSAML\XML\Shib13\AuthnResponse::setXML
-     * @test
-     * @return void
-     */
-    public function setXML()
-    {
-        $this->xml = new AuthnResponse();
-        $this->xml->setXML(static::XMLDOC);
-    }
-
-
     /**
      * @covers \SimpleSAML\XML\Shib13\AuthnResponse::doXPathQuery
      * @covers \SimpleSAML\XML\Shib13\AuthnResponse::getIssuer