[cuda_pathfinder] Add CUDA 12 support to cuda-pathfinder pixi environments and removing build-variants (NVIDIA#1365)

* Adding cu12 support

* Remove invalid noarch key from pixi.toml

Author: rparolin

cuda_pathfinder/pixi.lock

@@ -7,15 +7,18 @@ channels = ["conda-forge"]
 platforms = ["linux-64", "linux-aarch64", "win-64"]
 preview = ["pixi-build"]
 
-[workspace.build-variants]
-python = ["3.10.*", "3.11.*", "3.12.*", "3.13.*", "3.14.*"]
-
 [dependencies]
 cuda-pathfinder = { path = "." }
 
 [feature.test.dependencies]
 pytest = ">=6.2.4"
 
+[feature.cu12.system-requirements]
+cuda = "12"
+
+[feature.cu12.dependencies]
+cuda-version = ">=12.0,<13"
+
 [feature.cu13.system-requirements]
 cuda = "13"
 
@@ -24,6 +27,7 @@ cuda-version = ">=13.1,<14"
 
 [environments]
 default = { features = ["test"], solve-group = "default" }
+cu12 = { features = ["cu12", "test"], solve-group = "cu12" }
 cu13 = { features = ["cu13", "test"], solve-group = "cu13" }
 
 # TODO: check if these can be extracted from pyproject.toml
@@ -39,7 +43,7 @@ python = "*"
 setuptools = ">=64"
 
 [package.run-dependencies]
-python = "*"
+python = ">=3.10"
 
 [target.linux.tasks.test]
 cmd = ["pytest", "$PIXI_PROJECT_ROOT"]