add second time integrity check

corrlib/integrity.py

@@ -2,4 +2,9 @@ import datetime as dt
 
 
 def check_time_validity(created_at: dt.datetime, updated_at: dt.datetime) -> bool:
-    return not (created_at > updated_at)
+    # we expect created_at <= updated_at <= now
+    if created_at > updated_at:
+        return False
+    if updated_at > dt.datetime.now():
+        return False
+    return True