Removing CGNS support for versions older than 3.3.0

[eirikurj]

Purpose

This PR removes support for the old CGNS 3.2.1 library. The code will now only support a proper fortran module. Related to this we are updating our latest testing images to use CGNS 4.1.2. Once merged our images test for versions 3.3.0 and 4.1.2. Users still on 3.2.1 will thus need to upgrade.

Note that a new release should be made once merged.

Type of change

What types of change is it?
Select the appropriate type(s) that describe this PR

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (non-backwards-compatible fix or feature)
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no API changes)
• Documentation update
• Maintenance update
• Other (please describe)

Testing

Testing was performed both locally and on u20-gcc-ompi-latest.

Checklist

Put an x in the boxes that apply.

• I have run flake8 and black to make sure the code adheres to PEP-8 and is consistently formatted
• I have run unit and regression tests which pass locally with my changes
• I have added new tests that prove my fix is effective or that my feature works
• I have added necessary documentation