pycvodes/pykinsol failing to compile with python 3.9.1 about chempy HOT 4 CLOSED

I think this issue can be closed, since my build problems with pycvodes is a separate problem. At this point, I believe I will restart with a set of new, clean environments and see if I can find and reconcile any differences between my environment and the one in .drone.yml in chempy and pycvodes. Now, I am also getting test failure in `test_get_native__a_substance_no_composition` (solve0 and solve1 tests) in chempy with a `ValueError`. I think both of those use solvers from gsl, but I don't know if that is the cause. Regardless, I think it's clear there is something wrong in my build environment, which I may have caused. I hope to find and document it soon.

Those versions killed all the deprecations and warnings on both packages. I had made similar changes to pycvodes locally but somehow got a dirty directory and couldn't finish the build; I think I forgot to recursively update anyode. I still have the same compilation problems with `extern "C"` versus `extern` in `anyode_blas_lapack.hpp` however. I am now installing pycvodes from a local repo with the anyode url in `.gitmodules` pointed to a local repo with an altered `anyode_blas_lapack.hpp`. In sundials (`sundials_lapack.h`), they define the linkage of all the functions they declare as `extern "C"` for C++. If I understand correctly, the linkage (`extern "C"`) for a function is defined only once whereas you can use an external declaration (`extern`) where ever necessary. I mention this because now that I have pycvodes installed again, I am still unable to run the chempy tests requiring it and pycvodes is the only package that had a special installation. As soon as I can clear this hurdle, I hope to be able to document all the requirements and begin working on packaging.