toml changes for cpu only install

pyproject.toml

@@ -43,3 +43,20 @@ testpaths = ["tests"]
 python_files = ["test_*.py"]
 python_classes = ["Test*"]
 python_functions = ["test_*"]
+
+# target torch to cuda 12.8
+[tool.uv.sources]
+torch = [
+  { index = "pytorch-cpu", marker = "sys_platform != 'linux'" },
+  { index = "pytorch-cu128", marker = "sys_platform == 'linux'" },
+]
+
+[[tool.uv.index]]
+name = "pytorch-cpu"
+url = "https://download.pytorch.org/whl/cpu"
+explicit = true
+
+[[tool.uv.index]]
+name = "pytorch-cu128"
+url = "https://download.pytorch.org/whl/cu128"
+explicit = true