Add weekly cron job for base and template

[TimMonko]

Description

This adds a once-per-week scheduled run (cron job) to the github actions. This is the path of least annoyance, because folks can easily ignore the failed jobs. We could create a FAIL_TEMPLATE that gets reported, but this would complicate test_and_deploy and add another file in .github

But, at least folks can learn when dependency updates break their packages

This is a considerably simpler implementation of a cron job compared to #65 (which used reusables and multiple new files)

[TimMonko]

@guiwitz another quick one for you to review 😁

[TimMonko]

I picked Tuesday because that seems like one of the days where I get the least CI spam / cron jobs

[guiwitz]

I'm just wondering if some users might be puzzled why they get systematic messages from GitHub and wouldn't even know how to turn it off. I think there might be quite a large crowd that creates plugins without actually using GH at all. Should this maybe be an optional thing in the copier template?

[TimMonko]

I'm just wondering if some users might be puzzled why they get systematic messages from GitHub and wouldn't even know how to turn it off. I think there might be quite a large crowd that creates plugins without actually using GH at all. Should this maybe be an optional thing in the copier template?

Thank you for the perspective! I've long thought that the .github folder is something that should Just Work, as in a new user doesn't need to peer into its contents.

However, I think you are bringing up a point that if you get systematic messages from a failed cron job than it stops being something that Just Works, and starts being bothersome.

I'll have a think about it more. Maybe something that could go into "advanced maintenance options" in the template prompts. I don't want to fully clutter things up with a bunch of questions, like "do you want a cron job" is probably just as annoying.

Thanks!

[TimMonko]

Placing this in draft while I think about alternative ways to implement this