Fix _LazyBatchNorm import broken by torch 1.10.0

[calvinmccarter-at-lightmatter]

Fixes #22 .

This PR is necessitated by this PyTorch PR which is now part of 1.10.0 pytorch/pytorch#60982

Unfortunately, this PR will break onnx2pytorch for torch<1.10.0, so it is not ready to be merged until I fix this.
Edit: this PR now works with torch < 1.10.0 and torch >= 1.10.0.

[ControllableGeneration]

I installed torch 1.10.0 but the problem was not resolved. Editing onnx2pytorch/operations/batchnorm.py and change _LazyBatchNorm to _LazyNormBase fixes the problem!b the issue

[calvinmccarter-at-lightmatter]

@Talmaj - this PR is now ready for review.

Also resolves #25 (same as #23 ).

[Talmaj]

@calvinmccarter-at-lightmatter can you add to tox.ini a new test env for torch<=1.9.0 ?

[tox]
envlist = clean,py36,py37,py38,py38-torch19,py39

[testenv]
passenv =
    CIRCLE*
    KMP_DUPLICATE_LIB_OK
deps =
    -rrequirements.txt
    torch19: torch <= 1.9.0.
    pytest-cov
commands =
    pytest --cov --cov-append --cov-report term --cov-report html tests/

[calvinmccarter-at-lightmatter]

@Talmaj - done! and PR #27 is ready for review as well