Enable uv self-update via uv pip commands on Windows

[FredStober]

On windows, uv should be able to update itself when uv is installed into a virtual environment.

• The command you invoked (e.g., uv pip sync requirements.txt), ideally including the --verbose flag.

uv venv --seed test
test\Scripts\activate
pip install "uv==0.1.35"
uv pip install "uv==0.1.38"

Results under windows in error: failed to remove file <......>\test\Lib\site-packages\../../Scripts/uv.exe

The minimal example is just to show how to trigger the error. The same issue appears with a much more likely uv pip sync, whenever uv is listed as part of the requirements.

• The current uv platform

This affects all uv versions under windows (very likely due to the system limitations related to running processes).
There are different workarounds imaginable, so it would be nice if one could be implemented. Alternatively, uv should probably avoid even trying to do this and abort with a nicer error message, indicating that this is not supported - at least under windows, since it works fine on linux.

[charliermarsh]

Thanks -- I believe this is the same as #1368 and #1327.