Update Fallback Logo URL to Mage-OS Logo

Author: pykettk

app/code/Magento/Backend/view/adminhtml/templates/page/header.phtml

@@ -18,7 +18,7 @@ $part = $block->getShowPart();
         : ''; ?>
     <?php $logoSrc = $block->hasLogoImageSrc()
         ? $escaper->escapeHtml($block->getLogoImageSrc())
-        : 'images/magento-logo.svg'; ?>
+        : 'images/mage-os-logo.svg'; ?>
     <a href="<?= $escaper->escapeUrl($block->getHomeLink()); ?>"
        <?= /* @noEscape */ $edition; ?>
        class="logo">