Added 'final' class bypassing in Core's snippet-bootstrap file

Core/snippet-bootstrap.php

@@ -1,7 +1,11 @@
 <?php
 
 use Google\Cloud\Core\Testing\TestHelpers;
+use DG\BypassFinals;
 
 TestHelpers::snippetBootstrap();
 
 date_default_timezone_set('UTC');
+
+// Make sure that while testing we bypass the `final` keyword for the GAPIC client.
+BypassFinals::enable();