Remove cmake dynamic versioning

What is the bug

ICON needs to be built without Git. For example, via Spack.

How do you fix it

Removing the dynamic versioning that reads the git history.
CMake requirement is therefore back to 3.18.

How urgent is the bugfix

• I need it as soon as possible
• I can wait for a couple of days
• None of my current codes is directly affected

Mandatory steps before review

• Gitlab CI passes
• Bugfix is covered by additional unit tests
• Mark the merge request as ready by removing Draft:

Mandatory steps before merge

• Test coverage does not decrease
• Reviewed by a maintainer
• Incorporate review suggestions
• Remember to edit the commit message and select the proper changelog category (feature/bugfix/other)

You are not supposed to merge this request by yourself, the maintainers of fortran-support take care of this action!