Separate browsergym updates

[enyst]

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Give a summary of what the PR does, explaining any non-trivial design decisions

This PR proposes to put browsergym updates in their own group, to be reviewed separately from the rest.

The reason is that newer versions install nvidia-CUDA via a libvisualwebarena dependency

• this has lead to failed CI because of out of space errors
• we have torch and similar, set as optional deps under the evaluation poetry group (used for local embeddings), but I suppose we won't do that with browsergym

I seem to understand we will want visual web arena, so we may need to look into this. In any case, we have generally separated deps that are likely to break things, and this one looks like it needs its own.

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To run this PR locally, use the following command:

docker run -it --rm   -p 3000:3000   -v /var/run/docker.sock:/var/run/docker.sock   --add-host host.docker.internal:host-gateway   -e SANDBOX_RUNTIME_CONTAINER_IMAGE=docker.all-hands.dev/all-hands-ai/runtime:273f8b9-nikolaik   --name openhands-app-273f8b9   docker.all-hands.dev/all-hands-ai/openhands:273f8b9