fix: smoke test caught undeclared dependency on uv in cogames tests

[yatharth]

What this PR does

uv is not declared as a dependency in cogames's pyproject.toml. Yet it was used in some of cogames's test.

This PR removes that dependence.

Why does this PR do that

The smoke test in #4423 caught this issue.

As a stand-alone package, cogames's tests should not depend on any package not included in pyproject.toml as a regular dependency or dev dependency.

[yatharth]

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• feat: prompt user to publish public announcement in discord during metta publish #4527
• feat: run cogames smoke test from source code in child repo #4523
• refactor: reorder jobs in release-cogames.yml to be in execution order #4525
• feat: include package-specific tags in filtered history pushed to child repo during metta publish #4522
• feat: show dry-run preview of what would be pushed to child repo in metta publish #4521
• feat: add smoke test in cogames release workflow #4423
• fix: smoke test caught undeclared dependency on uv in cogames tests #4425 👈 (View in Graphite)
• fix: remove all imports from metta in cogames #4421 : 1 other dependent PR (#4422 )
• fix: manual dispatch of mettagrid/cogame release workflows was broken on certain branches #4419
• feat: wait for mettagrid PyPi release before publishing cogames to PyPi #4418
• feat: clearer warnings when using --force with metta publish #4516
• feat: pin cogames to specific mettagrid version before publishing #4417
• refactor: simplify git and versioning logic in metta publish.py #4416
• refactor: reorganise metta publish.py to prepare for downstream refactor #4415
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