Introduce Nox for Local and CI Test Automation. Start Writing a Contributors Guide.

This MR introduces the test automation tool Nox to pystencils, and adapts its CI to use Nox. The Nox setup includes automatic detection of the CUDA version, as well as external dependencies for the documentation build.

Alongside this, a Contributors Guide section is added to the docs and populated with some basic instructions.

We use the pycodegen/nox:alpine container for linting and type checking, and the nox:ubuntu24.04-cuda12.6 container for the testsuite and documentation build. At this time, these containers do not yet include an installation of waLBerla for testing the distributed data handling.

Also, type checking for the codegen and jit modules is enabled on the side.

noxfile.py

@@ -4,26 +4,21 @@ from typing import Sequence
 import os
 import nox
 import subprocess
-import re
 
 nox.options.sessions = ["lint", "typecheck", "testsuite"]
 
 
 def get_cuda_version() -> None | tuple[int, ...]:
-    query_args = ["nvcc", "--version"]
-    
+    smi_args = ["nvidia-smi", "--version"]
+
     try:
-        query_result = subprocess.run(query_args, capture_output=True)
+        result = subprocess.run(smi_args, capture_output=True)
     except FileNotFoundError:
         return None
 
-    matches = re.findall(r"release \d+\.\d+", str(query_result.stdout))
-    if matches:
-        match = matches[0]
-        version_string = match.split()[-1]
-        return tuple(int(v) for v in version_string.split("."))
-    else:
-        return None
+    smi_output = str(result.stdout).splitlines()
+    cuda_version = smi_output[-1].split(":")[1].strip()
+    return tuple(int(v) for v in cuda_version.split("."))
 
 
 def editable_install(session: nox.Session, opts: Sequence[str] = ()):
@@ -55,13 +50,13 @@ def typecheck(session: nox.Session):
 def testsuite(session: nox.Session, cupy_version: str | None):
     if cupy_version is not None:
         cuda_version = get_cuda_version()
-        if cuda_version is None or cuda_version[0] < 11:
+        if cuda_version is None or cuda_version[0] not in (11, 12):
             session.skip(
-                "No compatible installation of CUDA found - Need at least CUDA 11"
+                "No compatible installation of CUDA found - Need either CUDA 11 or 12"
             )
 
         cuda_major = cuda_version[0]
-        cupy_package = f"cupy-cuda{cuda_major}=={cupy_version}"
+        cupy_package = f"cupy-cuda{cuda_major}x=={cupy_version}"
         session.install(cupy_package)
 
     editable_install(session, ["alltrafos", "use_cython", "interactive", "testsuite"])