chore(rss): auto-generate feed.xml

Author: github-actions[bot]

feed.xml

@@ -5,7 +5,7 @@
   <link>https://kadubon.github.io/github.io/</link>
   <description>Research preprints and theoretical works by K. Takahashi</description>
   <language>en</language>
-  <lastBuildDate>Fri, 03 Apr 2026 17:29:01 +0900</lastBuildDate>
+  <lastBuildDate>Fri, 03 Apr 2026 17:34:04 +0900</lastBuildDate>
   <atom:link rel="self" type="application/rss+xml" href="https://kadubon.github.io/github.io/feed.xml" />
   <atom:author>
     <atom:name>K. Takahashi</atom:name>