RSS feed has bad dates

[mattip]

Please describe the bug or issue including how to reproduce it.

https://scientific-python.org/index.xml has

<pubDate>Mon, 01 Jan 0001 00:00:00 +0000</pubDate>

Add any other context about the problem here, screenshots, etc.

This renders poorly in my xss reader

[stefanv]

Interesting; I didn't realize anyone used the RSS feed from our non-blog sites!

I think the solution is to add a date field to each page (this is how it renders when there is no date).