fix RSS date format

src/stacosys/service/rssfeed.py

@@ -1,13 +1,15 @@
 #!/usr/bin/env python
 # -*- coding: UTF-8 -*-
 
-from datetime import datetime
+from datetime import datetime, timezone
 
 import markdown
 import PyRSS2Gen
 
 from stacosys.db import dao
 
+RFC_822_FORMAT = '%a, %d %b %Y %H:%M:%S +0000'
+
 
 class Rss:
     def __init__(self) -> None:
@@ -40,7 +42,7 @@ class Rss:
                     link=item_link,
                     description=markdownizer.convert(row.content),
                     guid=PyRSS2Gen.Guid(f"{item_link}{row.id}"),
-                    pubDate=row.published,
+                    pubDate=self._to_rfc822(row.published)
                 )
             )
 
@@ -54,3 +56,7 @@ class Rss:
         )
         with open(self._rss_file, "w", encoding="utf-8") as outfile:
             rss.write_xml(outfile, encoding="utf-8")
+
+    def _to_rfc822(self, dt):
+        return dt.replace(tzinfo=timezone.utc) \
+                 .strftime('%a, %d %b %Y %H:%M:%S %z')