Fix pixi run test: CUDA 13.3 pin lag + cython-test .so placement (#2180)

* Fix cuda-version pin lag breaking local pixi run test

The bindings were regenerated against CUDA 13.3.0 (cc50515), adding NVRTC
symbols (NVRTC_ERROR_BUSY, nvrtcBundledHeadersInfo, nvrtcGetBundledHeadersInfo),
but the pixi cuda-version pins stayed at 13.2 in cuda_bindings/pixi.toml and
cuda_core/pixi.toml. `pixi run test` then built 13.3-referencing Cython code
against a 13.2 nvrtc.h and failed with "'nvrtcBundledHeadersInfo' was not
declared in this scope". CI was unaffected because it builds wheels from
ci/versions.yml (13.3.0) rather than via pixi run test.

Bump the cuda-version pins (build-variants + feature.cu13) from 13.2.* to
13.3.* in both packages so the local toolkit matches the regenerated sources
and ci/versions.yml. Re-solved pixi.lock files accordingly.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* Place cython-test .so in tests/cython regardless of cwd

tests/cython/build_tests.py runs `build_ext --inplace`, which writes the
compiled .so relative to the current working directory. pixi runs the
build-cython-tests task from the project root, so the .so landed in the
package root instead of tests/cython/, where pytest imports it by bare module
name. The test only passed previously because a correctly-placed .so from an
earlier build persisted (gitignored); a clean checkout fails with
ModuleNotFoundError.

chdir to the script directory before build_ext --inplace so the .so lands next
to its .pyx in both cuda_bindings and cuda_core (kept aligned per #1978).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: rparolin

cuda_bindings/pixi.lock

@@ -10,7 +10,7 @@ preview = ["pixi-build"]
 [workspace.build-variants]
 python = ["3.10.*", "3.11.*", "3.12.*", "3.13.*", "3.14.*"]
 # Keep source-package metadata aligned with the consuming environment's CUDA major.
-cuda-version = ["12.*", "13.2.*"]
+cuda-version = ["12.*", "13.3.*"]
 
 [feature.test.dependencies]
 cuda-bindings = { path = "." }
@@ -74,7 +74,7 @@ CUDA_HOME = "$CONDA_PREFIX/Library"
 cuda-version = "12.*"
 
 [feature.cu13.dependencies]
-cuda-version = "13.2.*"
+cuda-version = "13.3.*"
 
 [environments]
 default = { features = ["test", "cython-tests"], solve-group = "default" }

cuda_bindings/pixi.toml

@@ -12,6 +12,7 @@
 
 from __future__ import annotations
 
+import os
 import sys
 from pathlib import Path
 
@@ -45,6 +46,13 @@ def main() -> None:
         compiler_directives={"freethreading_compatible": True},
     )
 
+    # `build_ext --inplace` places the compiled .so relative to the current
+    # working directory, but pixi runs this task from the project root. pytest
+    # imports each extension by bare module name (see test_cython.py), which
+    # only resolves when the .so sits in tests/cython (the dir pytest puts on
+    # sys.path). chdir here so the .so lands next to its .pyx regardless of the
+    # invoking cwd.
+    os.chdir(script_dir)
     sys.argv = [sys.argv[0], "build_ext", "--inplace"]
     setup(name="cuda_bindings_cython_tests", ext_modules=ext_modules)