Remove cmake version check in CMakeLists.txt

What is the new feature

No change of any fortran code, just removal of the cmake version check in CMakeLists.txt. It seems no longer necessary due to past changes related to the renaming of f90 suffixes to F90.

How is it implemented

Version check commented out and added a code line

cmake_policy(SET CMP0048 NEW)

which seems to be required if using an older cmake version as 3.18

Mandatory steps before review

• Gitlab CI passes (Hint: use make format for linting)
• New feature 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 fortan-support take care of this action!