Add hook for pydantic

[rokm]

The PyPi version of pydantic comes with all its modules compiled as cpython extensions. This prevents pyinstaller from properly discovering the dependant modules, both from the pydantic package itself and from the standard library.

Fixes pyinstaller/pyinstaller#5359.

[rokm]

Here are test matrices for before and after.

I suspect that the versions that were passing even before the changes are not compiled.

Older versions of pydantic on linux seem to be still failing with the same symptoms as before - I've verified that those are extension-compiled versions. And I suspect that this import is to blame. It is gone from pydantic 1.4 and later, so those work fine.

[bwoodsend]

We already have #57 but this looks a lot less scary so I'd definitely go with this one.

Closes #57.

[bwoodsend]

I take it then that you wish to drop support for anything below 1.4?

Realistically, I feel that this kind of self-induced mess is for package authors to clear up - not us.

[rokm]

I take it then that you wish to drop support for anything below 1.4?

Realistically, I feel that this kind of self-induced mess is for package authors to clear up - not us.

I don't think there's anything we can actually do about compiled versions below 1.4. If someone absolutely has to use pyinstaller with those old versions, they'll need to install the non-compiled variant.

[bwoodsend]

Ok then.

[Legorooj]

I seem to remember there being a discussion about reading the imports from python extension modules somewhere, but can't remember off the top of my head. Will look into it again when I tackle modulegraph in January.