Do not call `find_libpython` during `import clr` as Python.Runtime can find it on its own by lostmsu · Pull Request #1440 · pythonnet/pythonnet

What does this implement/fix? Explain your changes.

find_libpython spectacularly fails to find libpython for debug build of Python on latest Ubuntu (e.g. apt install python3-dbg; python3-dbg). It is also not necessary at runtime, since Python.Runtime can now find C API functions, since they are already loaded into the process.

Does this close any currently open issues?

Probably these:
#1388
#1412 (partially)