[Opm] Dropping DUNE 2.6 support for OPM 2022.10?

[Markus Blatt]

Hi,

I think until recently we still aimed to support DUNE 2.6 (for reasons not 100% obvious to me). With
the advent of DUNE 2.9 next month that would mean supporting 4 versions. That seems IMHO like a monstruous tasks.
Historically we always aimed to support at least 2 recent versions, which seems to make sense.

Hence my question is what versions we actually should support for the next release.

In my humble opinion we should drop support for 2.6. While this is the version in Ubuntu 20.04 LTS, the compiler
on that system does not allow compilation of OPM
  The next version 2.7 is still in Debian stable, Ubuntu impish 21.10 and we probably should support that one.

Cheers,

Markus
-- 

Markus Blatt
CEO @ OPM-OP AS, Heyerdahlsvei 12b, 0777 Oslo, Norway
https://opm-op.com | +4916097590858