Set monthly updates

genfeed.py

@@ -73,9 +73,12 @@ def main():
                 "docs": "https://www.rssboard.org/rss-specification",
                 "webMaster": "dozens@tilde.town (~dozens)",
                 "generator": "Python " + ".".join(map(str, sys.version_info[:3])),
-                "sy:updatePeriod": "weekly",
+                # Update on the first of every month, at midnight UTC
+                "sy:updatePeriod": "monthly",
                 "sy:updateFrequency": "1",
                 "sy:updateBase": "1971-01-01T00:00+00:00",
+                # One month, roughly, for clients that do not support mod_syndication
+                "ttl": 60 * 24 * 30,
                 "item": list(map(parse_book, csv.DictReader(sys.stdin))),
             }
         }