pyproject : add linux platform marker to uv torch source (#29177)

In tool.uv.sources, torch was unconditionally pinned to the custom
pytorch CPU index, which lacks macOS Darwin wheels and causes uv sync
to fail on macOS. Add the sys_platform == 'linux' marker to match the
existing Poetry dependencies configuration.

Assisted-by: Antigravity

Resolves: https://github.com/ggml-org/llama.cpp/issues/29176

pyproject.toml

@@ -55,7 +55,9 @@ url = "https://download.pytorch.org/whl/cpu"
 priority = "explicit"
 
 [tool.uv.sources]
-torch = { index = "pytorch" }
+torch = [
+    { index = "pytorch", marker = "sys_platform == 'linux'" },
+]
 
 [[tool.uv.index]]
 name = "pytorch"