Teach `datasette publish` to pin to `datasette<1.0` in a 0.x release

[simonw]

I just realized that when I ship Datasette 1.0 there may be automated deployments out there which could deploy the 1.0 version by accident, potentially breaking any customizations that aren't compatible with the 1.0 changes.

I can hopefully help avoid that by shipping one last entry in the 0.x series that ensures datasette publish pins to <1.0 when it installs Datasette itself.

[simonw]

This won't actually help that much if the user's GitHub Actions workflow does the equivalent of this:

pip install datasette
datasette publish cloudrun mydb.db ...

Since they'll get the 1.0 release too.

Since they'll need to make changes anyway, maybe a better solution is to document this and tell people they should use this instead:

datasette publish cloudrun mydb.db ... --branch 0.64.1

[simonw]

I can run a GitHub code search a week or so before the release to give me time to get in touch with anyone who has actions that look like they might break.