fix(vllm): fix typo in async server initialization

[omkarrr2533]

What does this PR do?

Fixes typos in async server initialization code.

Changes Made

1. Fixed typo in vllm_async_server.py initialization
2. Fixed run_unvicorn → run_uvicorn typo in all files:
   • verl/workers/rollout/vllm_rollout/vllm_async_server.py
   • verl/workers/rollout/utils.py
   • verl/workers/rollout/sglang_rollout/async_sglang_server.py
3. Code formatted with ruff (auto)

Testing

• [x] Code compiles without errors
• [x] No syntax issues detected
• [x] Ruff formatting passes
• [x] Mypy type checking passes
• [x] License headers verified

Checklist

• [x] My code follows the style guidelines of this project
• [x] I have performed a self-review of my own code
• [x] I have commented my code, particularly in hard-to-understand areas
• [x] My changes generate no new warnings
• [x] I have added tests that prove my fix is effective (N/A for typo fixes)

Notes

• Development on Windows; some pre-commit hooks were skipped due to platform differences
• Addressed review feedback from @gemini-code-assist

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