[MNT] address deprecation of load_module

[fkiraly]

load_module is deprecated and will be replaced by exec_module in python 3.12, this PR addresses that.

The fix is highly nontrivial - the crucial line was
imported_mod = module.load_module() for a module: SourceFileLoader,

which had to be replaced by the equivalent four (!) lines

spec = importlib.util.spec_from_file_location(module.name, module.path)
imported_mod = importlib.util.module_from_spec(spec)

# these two are also crucial due to the side effects
loader = spec.loader
loader.exec_module(imported_mod)

The deprecation message raised by load_module is highly unhelpful, and I had to reverse engineer this from a very helpful PR in nox, wntrblm/nox#498

[fkiraly]

FYI @yarnabrina - perhaps you see a quick fix to this? I'm not sure what to replace the deprecated logic by, is the problem.

[yarnabrina]

Sorry, I have not used exec_module ever. But the documented code seems be in a different format (for example, with arguments).

https://docs.python.org/3/library/importlib.html#importing-a-source-file-directly

If you can explain me what you are trying to do, for example why the if block is not enough and it has to go to eif block, I can try to think on this. Given this is a internal function, can you not control what is passed to this function?

[fkiraly]

Re the "what", the issue is simply that load_module is deprecated, and I am trying to preserve the logic of the affected code block by any means, without using load_module. There are no further constraints.

[fkiraly]

for posterity, this was highly non-trivial.
I reverse-engineered the solution from wntrblm/nox#498.

Any line imported_mod = module.load_module() for a module: SourceFileLoader can equivalently be replaced by apparently equivalent the four lines

spec = importlib.util.spec_from_file_location(module.name, module.path)
imported_mod = importlib.util.module_from_spec(spec)

# these two are also crucial due to the side effects
loader = spec.loader
loader.exec_module(imported_mod)

The deprecation message raised by load_module is highly unhelpful here.

[codecov-commenter]

Codecov Report

All modified lines are covered by tests ✅

Comparison is base (38cef3d) 83.60% compared to head (a2aa811) 83.60%.
Report is 1 commits behind head on main.

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Additional details and impacted files

@@           Coverage Diff           @@
##             main     #190   +/-   ##
=======================================
  Coverage   83.60%   83.60%           
=======================================
  Files          43       43           
  Lines        2843     2843           
=======================================
  Hits         2377     2377           
  Misses        466      466           

Files	Coverage Δ
skbase/lookup/_lookup.py	93.86% <100.00%> (+0.07%)	⬆️

... and 1 file with indirect coverage changes

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