Ease the process of code versioning

What is the requested feature?
Automate the code versioning process to have effective versioning of the code and maybe releases.

Is your request related to a specific problem?
I would like an easy, human readable, comparable way to discriminate versions of the public API (i.e. represented as xsd files https://github.com/GEOS-DEV/GEOS/issues/2971). Not sure a commit hash is the right way.

Describe the solution you'd like
I was thinking to something close to semver.

But, doing it manually is painful and time consuming.
So what about using a github-action like this one: https://github.com/ietf-tools/semver-action.
It will flow seamlessly for those using commit prefixes.
For the others, we could simply avoid the patch part and adopt a simple algorithm like this one:

If the PR needs a rebaseline (xsd change)  then bump major part
else bump minor part.

This action will make the next version available as a variable in the pipeline.
It should then be easy to patch the CMakeLists, a header file, xsd schemas, or whatever...

What to you think ?

Describe alternatives you've considered
n.a.

Additional context
n.a.

Work steps:

1. #3043
2. #3266
3. Add semver-action to compute next version based on semver
   1. Add version to code (CMakeLists, GEOS_VERSION in c++, version tag in schema)
   2. stop pushing the schema in PRs / generate it at merge step via the CI