Bug fix in dockerfile ARG vs ENV var (#446)

Author: praateekmahajan

Dockerfile

@@ -28,9 +28,11 @@ FROM rapidsai/ci-conda:cuda${CUDA_VER}-${LINUX_VER}-py${PYTHON_VER}
 LABEL "nemo.library"=${IMAGE_LABEL}
 WORKDIR /opt
 
+# Re-declare ARGs after new FROM to make them available in this stage
+ARG CUDA_VER
+
 # Install the minimal libcu* libraries needed by NeMo Curator
-ENV _CUDA_VER=${CUDA_VER}
-RUN conda create -y --name curator -c nvidia/label/cuda-${_CUDA_VER} -c conda-forge \
+RUN conda create -y --name curator -c nvidia/label/cuda-${CUDA_VER} -c conda-forge \
   python=3.10 \
   cuda-cudart \
   libcufft \