Add space between cancel and ban button

When banning a user, the modal has two buttons: cancel and ban. These
buttons are so close to each other that it's hard to see they are
separate buttons.
By putting each button on their own row, there is more space between
them.

src/shared/components/person/profile.tsx

@@ -693,6 +693,8 @@ export class Profile extends Component<
             >
               {I18NextService.i18n.t("cancel")}
             </button>
+          </div>
+          <div className="mb-3 row">
             <button
               type="submit"
               className="btn btn-secondary"