set NUM_WORKERS to 0 in test_cuda action (#3404)

It seems causing an OOM issue in the CUDA runner.

Signed-off-by: Jinzhe Zeng <[email protected]>

.github/workflows/test_cuda.yml

@@ -51,10 +51,11 @@ jobs:
     - run: python -m pip install -v -e .[gpu,test,lmp,cu12,torch] "ase @ https://gitlab.com/ase/ase/-/archive/8c5aa5fd6448c5cfb517a014dccf2b214a9dfa8f/ase-8c5aa5fd6448c5cfb517a014dccf2b214a9dfa8f.tar.gz"
       env:
         DP_VARIANT: cuda
-        NUM_WORKERS: 0
         DP_ENABLE_NATIVE_OPTIMIZATION: 1
     - run: dp --version
     - run: python -m pytest source/tests --durations=0
+      env:
+        NUM_WORKERS: 0
     - name: Download libtorch
       run: |
          wget https://download.pytorch.org/libtorch/cu121/libtorch-cxx11-abi-shared-with-deps-2.2.1%2Bcu121.zip -O libtorch.zip