Add a new optimizer

[pranayasinghcsmpl]

Fixes #869

Proposed Changes

• import nadam from torch.optim in wrap_torch.py
• create nadam function to handle parameters in wrap_torch.py
• update nadam optimizer in init.py

Checklist

• [ ] CONTRIBUTING guide has been followed.
• [ ] PR is based on the current GaNDLF master .
• [ ] Non-breaking change (does not break existing functionality): provide as many details as possible for any breaking change.
• [ ] Function/class source code documentation added/updated (ensure typing is used to provide type hints, including and not limited to using Optional if a variable has a pre-defined value).
• [ ] Code has been blacked for style consistency and linting.
• [ ] If applicable, version information has been updated in GANDLF/version.py.
• [ ] If adding a git submodule, add to list of exceptions for black styling in pyproject.toml file.
• [ ] Usage documentation has been updated, if appropriate.
• [ ] Tests added or modified to cover the changes; if coverage is reduced, please give explanation.
• [ ] If customized dependency installation is required (i.e., a separate pip install step is needed for PR to be functional), please ensure it is reflected in all the files that control the CI, namely: python-test.yml, and all docker files [1,2,3].

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[pranayasinghcsmpl]

@sarthakpati While linting (using black .) i am getting the following error:

error: cannot format D:\Workspace\gandlf\fork\GaNDLF\testing\entrypoints__init__.py: Cannot parse: 321:26: ) as e, Oh no! 💥 💔 💥 170 files left unchanged, 1 file failed to reformat

[sarthakpati]

@sarthakpati While linting (using black .) i am getting the following error:

error: cannot format D:\Workspace\gandlf\fork\GaNDLF\testing\entrypointsinit.py: Cannot parse: 321:26: ) as e, Oh no! 💥 💔 💥 170 files left unchanged, 1 file failed to reformat

@VukW or @szmazurek could you perhaps check this?

[szmazurek]

Hey there! I took a look and actually, I failed to replicate the error you are seeing @pranayasinghcsmpl, are you sure there were no syntax errors in your local code when you were running it? Also maybe try to call black -v . flag to see the output verbose. The rest of the failed black tests were due to unformatted files present, I have done the formatting and pushed changes, and now the black test is passing. Probably due to this failure the black did not format those other files and that's why the CI failed.

[pranayasinghcsmpl]

Thanks @szmazurek