Formalize strategy for upgrading minimum versions of dependencies

[fsimonis]

We have some statements regarding supported distro versions, but we have no clear statement on how we select and upgrade our minimum required versions.

This is essentially a follow-up of #16.

We need a statement on:

• What dictates our minimum required versions.
• That minimum required version updates are not considered breaking releases.
• What upper bound we actively test.
• How forward-compatible the project is and if changes warrant a bugfix release.
• What distros we directly support (2 LTS of Ubuntu)
• How we deal with different MPI implementations (OpenMPI vs MPICH on Fedora, what about Intel MPI / Windows MPI?)

Optionally:

• What distros we indirectly support if they meet the version requirements (Debian, Arch, Fedora)
• How we handle required bug fixes for indirectly supported distros

Where shall we put this in the docs? Under fundamentals? How shall we call this page?

[MakisH]

Where shall we put this in the docs? Under fundamentals? How shall we call this page?

Why not just a section in https://precice.org/installation-source-dependencies.html?

I would definitely not put it in the "Fundamentals": sounds rather a technical detail to me.

Alternatively, it could be a dedicated page under "Dev docs", just before or part of https://precice.org/dev-docs-release-strategy.html