How to update coq version for library

This is a note for maintainers of this repo.

To update the library to a new version of coq we need to:

1. Update the etc/coq-dpdgraph submodule to latest version
2. Update opam file to latest released version of coq
3. Update CI coq version
4. Push a tag on the HoTT repo
5. Update opam-coq-archive