Add kernels to Docker images

[ishitab02]

What does this PR do?

This PR adds the kernels package to both Docker images (trl and trl-dev) to resolve the installation issue.

Fixes #4398

Changes

• Added RUN uv pip install --system kernels to docker/trl/Dockerfile
• Added RUN uv pip install --system kernels to docker/trl-dev/Dockerfile

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• This PR fixes a typo or improves the docs (you can dismiss the other checks if that's the case).
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• Did you make sure to update the documentation with your changes?
• Did you write any new necessary tests?