[CI] Fix typo in uv install

[DN6]

What does this PR do?

Oversight. Messed up the syntax on the uv uninstall for existing transformers. Fixes. Run is successful
https://github.com/huggingface/diffusers/actions/runs/19223328887/job/54945294413 (some numerical test failures that I'll fix in a follow up)

Fixes # (issue)

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