Remove deprecated slot syntax

- Update slot to use syntax supported after Vue 2.6

webapp/components/AvatarMenu/AvatarMenu.vue

@@ -1,6 +1,6 @@
 <template>
   <dropdown class="avatar-menu" offset="8" :placement="placement">
-    <template slot="default" slot-scope="{ toggleMenu }">
+    <template #default="{ toggleMenu }">
       <a
         class="avatar-menu-trigger"
         :href="
@@ -15,7 +15,7 @@
         <ds-icon size="xx-small" name="angle-down" />
       </a>
     </template>
-    <template slot="popover" slot-scope="{ closeMenu }">
+    <template #popover="{ closeMenu }">
       <div class="avatar-menu-popover">
         {{ $t('login.hello') }}
         <b>{{ userName }}</b>

webapp/components/NotificationsTable/NotificationsTable.vue

@@ -1,6 +1,6 @@
 <template>
   <ds-table v-if="notifications && notifications.length" :data="notifications" :fields="fields">
-    <template slot="icon" slot-scope="scope">
+    <template #icon="scope">
       <ds-icon
         v-if="scope.row.from.post"
         name="comment"
@@ -12,7 +12,7 @@
         v-tooltip="{ content: $t('notifications.post'), placement: 'right' }"
       />
     </template>
-    <template slot="user" slot-scope="scope">
+    <template #user="scope">
       <ds-space margin-bottom="base">
         <client-only>
           <hc-user
@@ -27,7 +27,7 @@
         {{ $t(`notifications.reason.${scope.row.reason}`) }}
       </ds-text>
     </template>
-    <template slot="post" slot-scope="scope">
+    <template #post="scope">
       <nuxt-link
         class="notification-mention-post"
         :class="{ 'notification-status': scope.row.read }"
@@ -41,7 +41,7 @@
         <b>{{ scope.row.from.title || scope.row.from.post.title | truncate(50) }}</b>
       </nuxt-link>
     </template>
-    <template slot="content" slot-scope="scope">
+    <template #content="scope">
       <b :class="{ 'notification-status': scope.row.read }">
         {{ scope.row.from.contentExcerpt | removeHtml }}
       </b>