This commit adds two GitHub workflows that build and deploy CensorBib.
The "build" workflow is run on every push and verifies the validity of
the .bib file -- as seen by our build tool and *not* by LaTeX!
The "deploy" workflow is run whenenver a branch is merged into master,
at which point CensorBib is automatically built and deployed via GitHub
pages. This means has two advantages:
* First, I no longer need to manually build and deploy CensorBib, and
can point the domain censorbib.nymity.ch to GitHub pages.
* Second, CensorBib will also be available under
https://nullhypothesis.github.io/censorbib/
which may be helpful to users for who my domain is blocked.
