Avoid `asyncio-dangling-task` violations on shadowed bindings (#9215)
## Summary
Ensures that we avoid flagging cases like:
```python
async def f(x: int):
if x > 0:
task = asyncio.create_task(make_request())
else:
task = asyncio.create_task(make_request())
await task
```
Closes https://github.com/astral-sh/ruff/issues/9133.