Conform to podcasting 2.0

https://github.com/Podcastindex-org/podcast-namespace/blob/main/docs/1.0.md

.github/workflows/feed.yml

@@ -122,12 +122,13 @@ jobs:
           fi
         done
   feed:
+    # fails for now due to https://github.com/w3c/feedvalidator/issues/116
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v4
     - uses: ruby/setup-ruby@v1
       with:
-        ruby-version: '2.7'
+        ruby-version: '3.2'
         bundler-cache: true
     - name: Install dependencies
       run: bundle install

pages/podcast.rss

@@ -4,6 +4,7 @@ permalink: "/podcast.rss"
 
 <?xml version="1.0" encoding="UTF-8"?>
 <rss version="2.0"
+  xmlns:podcast="https://podcastindex.org/namespace/1.0"
   xmlns:atom="http://www.w3.org/2005/Atom"
   xmlns:itunes="http://www.itunes.com/dtds/podcast-1.0.dtd"
   xmlns:content="http://purl.org/rss/1.0/modules/content/"
@@ -26,6 +27,8 @@ permalink: "/podcast.rss"
 			<title>{{ site.title }}</title>
 		</image>
 		<itunes:image href="{{ site.url }}/images/artwork.jpg" />
+		<podcast:locked>no</podcast:locked>
+		<podcast:guid>8ce685ca-8f87-553d-bc13-67fdf9f5a3de</podcast:guid>
 
 		<language>{{ site.lang }}</language>
 		<pubDate>{{ site.time | date_to_rfc822 }}</pubDate>