Retire the Pages site; the portal serves this page now

GitHub Pages is switched off for this repository and
pydevices.github.io/<repo>/ is served from PyDevices.github.io, at the same
URL, from a single generated page that shares the org chrome rather than
carrying its own copy of it.

So .site/ and the deploy workflow have nothing left to publish: the workflow
was still running on every push and writing to a gh-pages branch nothing
serves.

Author: bdbarnett