fix(list): add font-family style to subheader (#3056)

Author: chouclee

src/lib/list/list.scss

@@ -100,6 +100,7 @@ $mat-dense-three-line-height: 76px;
   padding: $mat-list-side-padding;
   margin: 0;
 
+  font-family: $mat-font-family;
   font-size: $secondary-size;
   font-weight: 500;