Check `python/uv/` folder with `mypy` (#7891)
It used to report:
```
ยป mypy
python/uv/_build_backend.py:40: error: Incompatible types in assignment (expression has type "list[str]", variable has type "CompletedProcess[bytes]") [assignment]
python/uv/_build_backend.py:41: error: Value of type "CompletedProcess[bytes]" is not indexable [index]
python/uv/_build_backend.py:46: error: Value of type "CompletedProcess[bytes]" is not indexable [index]
Found 3 errors in 1 file (checked 6 source files)
```
So, I had to fix this problem by renaming the `result` var.
