Prepare release 2.1.0

[robertodr]

Prepare the next release

Todos

• Developer Interest
  • [X] Updated version_info.hpp with version bump
  • [x] Updated xcfun.cmake with version bump
  • [x] Updated conf.py with version bump
  • [x] Updated C++, C, and Fortran host examples with version bump
  • [x] Updated CHANGELOG.md
  • [x] Updated .zenodo.json
  • [x] Updated documentation to include new ways of installing the package (conda and spack)

Status

• [x] Ready to go

[robertodr]

@bast do we want to pull in also #127? It is very close to the finish line...

[bast]

@bast do we want to pull in also #127? It is very close to the finish line...

catching up now (email deluge ...). i am looking at #127

[bast]

127 is now in and I made it conflict. Should we rebase this PR?

[robertodr]

Just rebased.