fix invalid class reference

\Foo\Bar\Baz is used as a dummy class in there, so it should not be
referenced using ::class.

\Foo\Bar\Baz class is present in
phpunit\php-token-stream\tests\_fixture\classExtendsNamespacedClass.php
but it is completely unrelated and not autoloaded.

tests/Util/TestTest.php

@@ -34,7 +34,7 @@ public function testGetExpectedException(): void
         );
 
         $this->assertArraySubset(
-            ['class' => \Foo\Bar\Baz::class, 'code' => null, 'message' => ''],
+            ['class' => 'Foo\Bar\Baz', 'code' => null, 'message' => ''],
             Test::getExpectedException(\ExceptionTest::class, 'testThree')
         );