[Dune] Dune 2.7.0 Release Candidate 2 ready

[Christoph Grüninger]

Dear Dune users and developers,
I just pushed Dune 2.7.0 Release Candidate 2 to Git and the tarballs to
our website. See
https://dune-project.org/download/2.7.0rc2/dune-common-2.7.0rc2.tar.gz
et al.

I did not receive direct feedback, but thanks for all the folks creating
merge requests and opening bugs (Markus, Janick, Christian, …)!

I plan to make the release next weekend, unless there are severe issues
found.

Bye
Christoph