Update to latest release of versioneer (0.29)

[thehrh]

Expected to be Python 3.11 and 3.12 compatible.

Some tests done after updating versioneer (see #779 (comment)):

• successful installation of PISA with Python 3.10.14, version number returned by pisa.__version__ agrees with version in package metadata (pisa.egg-info/PKG-INFO)
• using Python 3.12.5, I was able to execute the updated copy of versioneer.py (0.29) in the source tree (python versioneer.py setup), and also perform the vendored mode install using the pip-installed versioneer package (also 0.29)

Not explicitly tested (maybe someone else could verify by trying something similar to the above using this branch):

• Python 3.8 compatibility (according to https://github.com/python-versioneer/python-versioneer?tab=readme-ov-file#the-versioneer, it is also supported)

[thehrh]

Odd that the builds now fail. I sometimes get the exact same problem which I can prevent via export CFLAGS=-I<whatever numpy.get_include() returns> before running the setup (which I thought would be addressed by https://github.com/icecube/pisa/blob/master/setup.py#L217C34-L217C53).

It might have to do with https://github.com/icecube/pisa/blob/master/setup.py#L283 (yeah, that seems to be it, the new versioneer overwrites "build_ext", while the old one doesn't seem to do so).