fix(credits): remove undefined $podcast variable from page layout

fixes #359

themes/cp_app/pages/_layout.php

@@ -51,7 +51,7 @@
         <?= $this->renderSection('content') ?>
     </main>
     <footer class="container flex justify-between px-2 py-4 mx-auto text-sm text-right border-t border-subtle">
-        <?= render_page_links(null, $podcast->handle) ?>
+        <?= render_page_links() ?>
         <small><?= lang('Common.powered_by', [
                 'castopod' => '<a class="underline hover:no-underline focus:ring-accent" href="https://castopod.org/" target="_blank" rel="noreferrer noopener">Castopod</a>',
             ], null, false) ?></small>