Show media import button only on Media Library

We are injecting an Import button, in order to guide people on import media files while on Media Library.
But currently that button show up everywhere, on all post types.

This small change makes the button visible only in the Media Library.

src/Exporter.php

@@ -115,7 +115,7 @@ public function add_import_button(): void
         ?>
         <script>
             jQuery(function(){
-                jQuery(".wrap .page-title-action")
+                jQuery(".upload-php .wrap .page-title-action")
                     .after('<a href="upload.php?page=media-picker" class="add-new-h2"><?php esc_html_e('Import Greenpeace Media', 'planet4-master-theme-backend'); ?></a>');
             });