GitLab

Removes numpy dependency from test_gpu.py test and re-enables Python tests for Python 3.6.

The inaccuracy was caused by ONNX round requires nearest integer rounding for halway (0.5) cases.
std::round rounds away from zero, thus giving wrong results with halfway cases.
Replaced std::round with std::nearbyint which uses the correct rounding by default.

Fixes an issue that comes up for variable input slice with steps set manually in ONNX to default 1's.

Simplifies dimensions_of instructions to a literal when possible.
Intended to be used after the split_single_dyn_dim pass.

Disable python tests on Python 3.6 temporarily till we remove numpy dependencies from the tests using them.
Different versions of Python are compatible with different versions of numpy, so we need to remove numpy dependency.

Since opset version 18, the Split operator allows splitting into unevenly sized outputs when the split input is not present, and a num_outputs attribute has been introduced.