Fix VueIntersect single-element warning in notifications section

The <intersect> in sections/Notifications.vue wrapped four <placeholder>
elements directly. vue-intersect requires exactly one child (it checks
$slots.default.length and observes $slots.default[0]), so it logged
'[VueIntersect] You may only wrap one element in a <intersect> component.'
and only observed the first placeholder. Wrap the placeholders in a single
<div> so the slot has one root element.

resources/assets/components/sections/Notifications.vue

@@ -167,10 +167,12 @@
 
 						<div v-else>
 							<intersect v-if="hasLoaded && canLoadMore" @enter="enterIntersect">
-								<placeholder small style="margin-top: -6px" />
-								<placeholder small/>
-								<placeholder small/>
-								<placeholder small/>
+								<div>
+									<placeholder small style="margin-top: -6px" />
+									<placeholder small/>
+									<placeholder small/>
+									<placeholder small/>
+								</div>
 							</intersect>
 
 							<div v-else class="d-block" style="height: 10px;">