Remove usages of legacy importlib API.

[bwoodsend]

Motivation

The Python >= 3.10 compatible usages of importlib added in 277ff54 can be safely applied to any version of Python >= 3.5 which covers the full range that Hydra supports.

Getting rid of the old deprecated API, asides from cleaning up, will keep Hydra compatible with PyInstaller if PyInstaller doesn't get cold feet and revert its dropping of support for the legacy API (pyinstaller/pyinstaller#7344).

Have you read the Contributing Guidelines on pull requests?

Yes

Test Plan

(How should this PR be tested? Do you require special setup to run the test or repro the fixed bug?)

Standard CI/CD testing should be sufficient.

Related Issues and PRs

(Is this PR part of a group of changes? Link the other relevant PRs and Issues here. Use https://help.github.com/en/articles/closing-issues-using-keywords for help on GitHub syntax)

None.

[bwoodsend]

Remaining failures look sufficiently irrelevant to call background noise.

[bwoodsend]

@Jasha10 ?

[Jasha10]

Thanks for the ping @bwoodsend! We should be able to merge this shortly.

[omry]

Any concerns about compatibility with supported legacy Python versions?

[bwoodsend]

No, because current hydra doesn't support Python 3.5.

[Jasha10]

Thanks again @bwoodsend.
One relatively minor nit / question:

[omry]

No, because current hydra doesn't support Python 3.5.

This code is running on 3.6 to 3.9, wasn't it?

                        if sys.version_info < (3, 10):
                            m = importer.find_module(modname)  # type: ignore

[Jasha10]

This code is running on 3.6 to 3.9, wasn't it?

Yes. I introduced that if < (3, 10)-block in PR #2183 because the code was working for 3.6-3.9 but it did not work for python3.10.

[omry]

This code is running on 3.6 to 3.9, wasn't it?

Yes. I introduced that if < (3, 10)-block in PR #2183 because the code was working for 3.6-3.9 but it did not work for python3.10.

Gotcha. I did seem unfamiliar :)