Remove the C API

See Test the next Python to estimate how many C extension modules would be broken by a C API change, like removing a function.

One proposed alternative to a new better C API is no C API at all. The reasoning is that since existing solutions are already available, complete and reliable:

We do not need to have one for python itself.

However, this approach has lots of open questions without satisfying answers:

What about the long tail of C extensions on PyPI which still use the C extension? Would it mean a new Python without all these C extensions on PyPI?

Moreover, lots of project do not use those solution, and the C API is part of Python success. For example, there would be no numpy without the C API, and one can look at Consumers of the Python C API to see others examples.

Removing it would negatively impact those projects, so this doesn’t sound like a workable solution.