Replace link with button in index notifications

app/views/notifications/index.html.erb

@@ -5,7 +5,7 @@
       <%= t("notifications.index.title") %>
     </h1>
 
-    <%= link_to t("notifications.index.mark_all_as_read"),
+    <%= button_to t("notifications.index.mark_all_as_read"),
                   mark_all_as_read_notifications_path,
                   method: :put,
                   class: "button hollow float-right-medium" %>

spec/system/notifications_spec.rb

@@ -74,7 +74,7 @@ describe "Notifications" do
     click_notifications_icon
 
     expect(page).to have_css(".notification", count: 2)
-    click_link "Mark all as read"
+    click_button "Mark all as read"
 
     expect(page).to have_css(".notification", count: 0)
   end