Add horizontal line to admin sidebar (#4417)

* feat(admin): add horizontal line to sidebar. Closes #4098

* fix: lint css file

* fix: tweak css

* chore: go mod tidy

* fix: another css fix

web/components/admin/MainLayout.tsx

@@ -62,6 +62,10 @@ const EditOutlined = dynamic(() => import('@ant-design/icons/EditOutlined'), {
   ssr: false,
 });
 
+const DownloadOutlined = dynamic(() => import('@ant-design/icons/DownloadOutlined'), {
+  ssr: false,
+});
+
 const FediverseOutlined = dynamic(() => import('../../assets/images/icons/fediverse.svg'), {
   ssr: false,
 });
@@ -269,9 +273,18 @@ export const MainLayout: FC<MainLayoutProps> = ({ children }) => {
       icon: <ExperimentOutlined />,
       children: integrationsMenu,
     },
+    upgradeVersion && {
+      type: 'divider',
+      key: 'upgrade-divider',
+    },
     upgradeVersion && {
       key: '/admin/upgrade',
-      label: <Link href="/admin/upgrade">{upgradeMessage}</Link>,
+      label: (
+        <Link href="/admin/upgrade">
+          <strong>{upgradeMessage}</strong>
+        </Link>
+      ),
+      icon: <DownloadOutlined />,
     },
     {
       key: '/admin/help',