[TODO] Add a banner linking the packaging ecosystem survey

[webknjaz]

Issue Description

This one: https://anaconda.surveymonkey.com/r/py-package-2025

I'm thinking this could be done through a Sphinx extension, similar to what I did in the pip repo years ago.

cc @pradyunsg any other integration ideas? Other ways of plugging it into Furo?

Code of Conduct

• I am aware that participants in this repository must follow the PSF Code of Conduct.

[pradyunsg]

Furo lets you add a site-wide announcement. That's probably a reasonable choice for this.