Remove unneeded property title_id from Entry

src/library/library.cr

@@ -128,7 +128,7 @@ class Library
       .each do |e|
         break if recently_added.size > 12
         last = recently_added.last?
-        if last && e[:entry].title_id == last[:entry].title_id &&
+        if last && e[:entry].book.id == last[:entry].book.id &&
            (e[:date_added] - last_date_added.not_nil!).duration < 1.day
           # A NamedTuple is immutable, so we have to cast it to a Hash first
           last_hash = last.to_h