fix: update rss published to pubDate

This update ensures we are following RSS spec, more info:
https://www.rssboard.org/rss-specification#ltpubdategtSubelementOfLtitemgt

src/rss.njk

@@ -4,6 +4,7 @@ layout: null
 eleventyExcludeFromCollections: true
 excludeFromSitemap: true
 ---
+
 <?xml version="1.0" encoding="utf-8"?>
 <feed xmlns="http://www.w3.org/2005/Atom">
 <title>{{ meta.siteName }}</title>
@@ -19,10 +20,8 @@ excludeFromSitemap: true
     <id>{{ meta.url }}{{ post.url }}</id>
     <title>{{ post.data.title | escape }}</title>
     <link href="{{ meta.url }}{{ post.url }}" />
-    <published>{{ post.date }}</published>
-    {%- for tag in post.data.tags %}
-    <category term="{{ tag }}" />
-    {%- endfor %}
+    <pubDate>{{ post.date }}</pubDate>
+    {%- for tag in post.data.tags %}<category term="{{ tag }}" />{%- endfor %}
     <content type="html">{{ post.content | escape }}</content>
     </entry>
 {% endfor %}