Update Theme-Minimal for 30.X

I've done these custom CSS changes locally, but don't have time to PR them just yet. If somebody could bump Theme-Minimal with these and verify it looks good, that would be great!

New sidebar/top-bar related CSS changes:
```css
.filtered-list-toolbar.btn-toolbar {
  background-color: var(--primary-1);
}

.sidebar-pane .sidebar {
  background-color: var(--primary-1);
}
```