Dune 2.6 and Dune 2.7 compatible with dumux 3.2?

For the 3.2 release, we want to be dependent on dune 2.7, correct? This should be mentioned in:

• change log with reasons why.
• all install scripts
• website under installation instructions

TODOs

• After release 3.2 add note to the change log that 2.12 is no longer supported and
• Write email to users about above.
• After release 3.2 increase dependency to Dune 2.7

Current proposal for the testing plan during and after release 3.2 (as soon as a release branch is created)

Dune version -->	2.5	2.6	2.7	master
Dumux master			x	x
Dumux 3 (latest release 3.2)		x	x
Dumux 2 (latest release 2.12)