fix(ui): fix color of hovering over menu buttons in top nav bar (#10125)

Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/10125
Reviewed-by: 0ko <0ko@noreply.codeberg.org>
Co-authored-by: Robert Wolff <mahlzahn@posteo.de>
Co-committed-by: Robert Wolff <mahlzahn@posteo.de>

web_src/css/modules/navbar.css

@@ -42,6 +42,7 @@
 }
 
 #navbar a.item:hover, #navbar a.item:focus,
+#navbar div.ui.dropdown:hover,
 #navbar button.item:hover, #navbar button.item:focus {
   background: var(--color-nav-hover-bg);
 }