Use strftime to format date and datetimes

lib/music_library/records/record.ex

@@ -227,7 +227,7 @@ defmodule MusicLibrary.Records.Record do
     end
   end
 
-  def format_as_date(purchased_at) do
-    "#{purchased_at.day}/#{purchased_at.month}/#{purchased_at.year}"
+  def format_as_date(dt) do
+    Calendar.strftime(dt, "%d/%m/%Y")
   end
 end

lib/music_library/scrobble_activity.ex

@@ -81,7 +81,7 @@ defmodule MusicLibrary.ScrobbleActivity do
       |> DateTime.from_unix!()
       |> DateTime.shift_zone!(timezone)
 
-    "#{ldt.day}/#{ldt.month}/#{ldt.year} #{ldt.hour}:#{ldt.minute}"
+    Calendar.strftime(ldt, "%d/%m/%Y %X")
   end
 
   defp recent_release_ids(recent_tracks) do