chore: book date fixes

src/feeds/books.liquid

@@ -11,7 +11,7 @@ permalink: /books.xml
   <entry>
     <title>{{ book.title | escape }}</title>
     <link href="{{book.link}}" />
-    <updated>{{ book.finished | date: "%m.%d.%Y" }}</updated>
+    <updated>{{ book.started  | date: "%m.%d.%Y" }}</updated>
     <id>{{ book.link }}</id>
     <content type="html"></content>
   </entry>

src/feeds/json/books.11ty.liquid

@@ -13,7 +13,7 @@ permalink: '/books.json'
   "title": "{{ book.title | escape }}",
   "url": "{{ book.link }}",
   "content_text": "",
-  "date_published": "{{ book.finished | date: "%Y-%m-%dT%H:%M:%S-08:00" }}"
+  "date_published": "{{ book.started | date: "%Y-%m-%dT%H:%M:%S-08:00" }}"
   }{% if not forloop.last %},{% endif %}
 {% endfor %}
 ]