Updated the unit test controller to save the attribute

Author: saravananvelu

dev/tests/integration/testsuite/Magento/Catalog/Controller/Adminhtml/Product/AttributeTest.php

@@ -147,7 +147,7 @@ public function testWrongAttributeCode()
         /** @var \Magento\Framework\Message\Error $message */
         $message = $messages->getItemsByType('error')[0];
         $this->assertEquals(
-            'Attribute code "_()&&&?" is invalid. Please use only letters (a-z),'
+            'Attribute code "_()&&&?" is invalid. Please use only letters (a-z or A-Z),'
             . ' numbers (0-9) or underscore(_) in this field, first character should be a letter.',
             $message->getText()
         );