# Description

This PR adds stricter interpretation rules to value specified in
sb3_ppo_cfg.yaml, disallowing eval on any dict, which my contain
arbitrary code that makes program vulnerable.

Now, `eval` is got rid of, only str that start with `nn.` can be used to
only import the module from torch.nn. That seems to cover all usage for
lab so far, I can make more accommodations if there are more cases but
it seems like it is currently sufficient.

Fixes # (issue)

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## Type of change

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- Bug fix (non-breaking change which fixes an issue)

## Screenshots

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## Checklist

- [x] I have run the [`pre-commit` checks](https://pre-commit.com/) with
`./isaaclab.sh --format`
- [ ] I have made corresponding changes to the documentation
- [x] My changes generate no new warnings
- [ ] I have added tests that prove my fix is effective or that my
feature works
- [x] I have updated the changelog and the corresponding version in the
extension's `config/extension.toml` file
- [x] I have added my name to the `CONTRIBUTORS.md` or my name already
exists there

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Signed-off-by: ooctipus <zhengyuz@nvidia.com>
Co-authored-by: Mayank Mittal <12863862+Mayankm96@users.noreply.github.com>
Co-authored-by: Kelly Guo <kellyg@nvidia.com>