Prevent groups names in the top bar from wrapping

If there was not enough space for all of the items in the top bar, the
group name could end up wrapping. This tended to happen when the group
name was long, the sidebar was narrow and the search input was active.

src/styles/sidebar/components/group-list.scss

@@ -6,6 +6,11 @@
   align-items: center;
   color: $grey-6;
   display: flex;
+
+  // Prevent label from wrapping if top bar is too narrow to fit all of its
+  // items.
+  flex-shrink: 0;
+
   font-size: $body2-font-size;
   font-weight: bold;
 }