0️⃣ Support null dates

[agoose77]

Fixes rendering of "now" dates (null)

[changeset-bot]

🦋 Changeset detected

Latest commit: b9caefe

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 12 packages

Name	Type
@myst-theme/frontmatter	Patch
@myst-theme/providers	Patch
@myst-theme/diagrams	Patch
@myst-theme/jupyter	Patch
@myst-theme/site	Patch
@myst-theme/styles	Patch
@myst-theme/common	Patch
@myst-theme/icons	Patch
@myst-theme/book	Patch
@myst-theme/article	Patch
myst-to-react	Patch
myst-demo	Patch

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[rowanc1]

What is the use case for this? Can we send through "today" instead? null-ish to me means no date.

I can (maybe) see that a preprint/blog gets a today string, that is recognized by the CLI (not the theme) and then serialized to the frontend as the date it was built on. That is pretty dangerous though - it means all your blog posts are always written "today" whenever you rerender them (which is probably not what people want).

I don't know if I understand the use case where we want the frontend to show today's date whenever you refresh .. ?

[agoose77]

We discuss this over at mystmd, but the high level is that implicit 'today' is a bad thing. I'm closing this pr.