feat(a11y): use <time> tag for dates everywhere

src/components/tasks/partials/date-table-cell.vue

@@ -1,6 +1,8 @@
 <template>
 	<td v-tooltip="+date === 0 ? '' : formatDate(date)">
-		{{ +date === 0 ? '-' : formatDateSince(date) }}
+		<time :datetime="date ? formatISO(date) : null">
+			{{ +date === 0 ? '-' : formatDateSince(date) }}
+		</time>
 	</td>
 </template>
 

src/components/tasks/partials/kanban-card.vue

@@ -28,9 +28,9 @@
 			<span class="icon">
 				<icon :icon="['far', 'calendar-alt']"/>
 			</span>
-			<span>
+			<time :datetime="formatISO(task.dueDate)">
 				{{ formatDateSince(task.dueDate) }}
-			</span>
+			</time>
 		</span>
 		<h3>{{ task.title }}</h3>
 		<progress

src/components/tasks/partials/singleTaskInList.vue

@@ -39,14 +39,16 @@
 				:user="a"
 				v-for="(a, i) in task.assignees"
 			/>
-			<i
+			<time
+				:datetime="formatISO(task.dueDate)"
 				:class="{'overdue': task.dueDate <= new Date() && !task.done}"
+				class="is-italic"
 				@click.prevent.stop="showDefer = !showDefer"
 				v-if="+new Date(task.dueDate) > 0"
 				v-tooltip="formatDate(task.dueDate)"
 			>
 				- {{ $t('task.detail.due', {at: formatDateSince(task.dueDate)}) }}
-			</i>
+			</time>
 			<transition name="fade">
 				<defer-task v-if="+new Date(task.dueDate) > 0 && showDefer" v-model="task" ref="deferDueDate"/>
 			</transition>