Set MATURIN_PEP517_ARGS in readthedocs build

Specifically in the pre_create_environment step. Xref https://docs.readthedocs.com/platform/stable/build-customization.html#extend-or-override-the-build-process

Author: weiji14

.readthedocs.yml

@@ -5,6 +5,9 @@ build:
   os: "ubuntu-24.04"
   tools:
     python: "mambaforge-23.11"
+  jobs:
+    pre_create_environment:
+      - export MATURIN_PEP517_ARGS="--features cuda,pyo3";
 
 # Build documentation in the docs/ directory with Sphinx
 sphinx: