fix(side-nav-menu): fix a11y warnings

- remove role attributes from SideNavMenuItem
- remove "aria-haspopup" from SideNavMenu

src/UIShell/SideNav/SideNavMenu.svelte

@@ -24,7 +24,6 @@
 <li class:bx--side-nav__item="{true}" class:bx--side-nav__item--icon="{icon}">
   <button
     type="button"
-    aria-haspopup="true"
     aria-expanded="{expanded}"
     class:bx--side-nav__submenu="{true}"
     {...$$restProps}

src/UIShell/SideNav/SideNavMenuItem.svelte

@@ -18,9 +18,8 @@
   export let text = undefined;
 </script>
 
-<li role="none" class:bx--side-nav__menu-item="{true}">
+<li class:bx--side-nav__menu-item="{true}">
   <a
-    role="menuitem"
     aria-current="{isSelected ? 'page' : undefined}"
     href="{href}"
     class:bx--side-nav__link="{true}"