Force jaxlib CUDA build with pixi GPU environment

Co-authored-by: Diego Ferigo <diego.ferigo@iit.it>

pyproject.toml

@@ -206,10 +206,14 @@ pytest-icdiff = "*"
 robot_descriptions = "*"
 
 [tool.pixi.feature.gpu]
-dependencies = { cuda-version = "12.*", cuda-cupti = "*" }
 platforms = ["linux-64"]
 system-requirements = { cuda = "12.1" }
 
+[tool.pixi.feature.gpu.dependencies]
+cuda-cupti = "*"
+cuda-version = "12.*"
+jaxlib = {version = "*", build = "*cuda*"}
+
 [tool.pixi.pypi-dependencies]
 jaxsim = { path = "./", editable = true }