epath depends on backport package importlib_resources

[johannbrehmer]

etils.epath depends on the importlib_resources library here.

importlib_resources is a backport library of the standard library importlib.resources for python<3.9. If I'm not mistaken, in all Python versions supported by etils, that's no longer necessary; instead one should just use the standard library importlib.resources.

I believe the current code leads to issues with some packaging tools like pex, which are "smart" about not installing backport packages. This makes it difficult to use etils with such tools.

[johannbrehmer]

Ah, I just saw that this is already being discussed and being fixed in #722 .