build: 🔧 use yaml in front matter data instead of json

src/feed.njk

@@ -1,17 +1,11 @@
----json
-{
-  "permalink": "feed.xml",
-  "eleventyExcludeFromCollections": true,
-  "metadata": {
-    "title": "Sebin's Blog",
-    "description": "Writing about stuff I have vague interests in and commenting on stuff I read.",
-    "language": "en",
-    "base": "https://blog.sebin-nyshkim.net/",
-    "author": {
-      "name": "Sebin Nyshkim"
-    }
-  }
-}
+---
+permalink: feed.xml
+eleventyExcludeFromCollections: true
+metadata:
+  title: Sebin's Blog
+  description: Writing about stuff I have vague interests in and commenting on stuff I read.
+  language: en
+  base: 'https://blog.sebin-nyshkim.net/'
 ---
 <?xml version="1.0" encoding="utf-8"?>
 <feed xmlns="http://www.w3.org/2005/Atom" xml:lang="{{ metadata.language or page.lang }}">