Install scipy-stubs in bpr CI

Author: inducer

.github/workflows/ci.yml

@@ -42,7 +42,7 @@ jobs:
                 curl -L -O https://tiker.net/ci-support-v0
                 . ./ci-support-v0
                 build_py_project_in_conda_env
-                cipip install pytest pyfmmlib scipy matplotlib pyvisfile
+                cipip install pytest pyfmmlib scipy scipy-stubs matplotlib pyvisfile
                 cipip install basedpyright
                 basedpyright