Update nightly.yml to remove IMPORTER=1 in package validation. (#226)

* Update nightly.yml to fix wheel building issues.

* Update setup_venv.sh to only install torch+cu116 if IMPORTER=1 is set.

.github/workflows/nightly.yml

@@ -65,11 +65,11 @@ jobs:
     - name: Build and validate the package
       run: |
         cd $GITHUB_WORKSPACE
-        IMPORTER=1 ./setup_venv.sh
+        ./setup_venv.sh
         source shark.venv/bin/activate
         package_version="$(printf '%(%Y%m%d)T.${{ github.run_number }}')"
         SHARK_PACKAGE_VERSION=${package_version} \
-        pip wheel -v -w wheelhouse . --extra-index-url https://download.pytorch.org/whl/nightly/cpu  -f https://github.com/llvm/torch-mlir/releases -f https://github.com/nod-ai/SHARK-Runtime/releases
+        pip wheel -v -w wheelhouse . --pre -f https://download.pytorch.org/whl/nightly/torch -f https://github.com/llvm/torch-mlir/releases -f https://github.com/nod-ai/SHARK-Runtime/releases
         # Install the built wheel
         pip install ./wheelhouse/nodai*
         # Validate the Models

setup_venv.sh

@@ -108,7 +108,7 @@ fi
 
 $PYTHON -m pip install -e . --extra-index-url https://download.pytorch.org/whl/nightly/cpu -f https://github.com/llvm/torch-mlir/releases -f https://github.com/${RUNTIME}/releases
 
-if [[ $(uname -s) = 'Linux' ]]; then
+if [[ $(uname -s) = 'Linux' && ! -z "${IMPORTER}" ]]; then
   $PYTHON -m pip uninstall -y torch torchvision
   $PYTHON -m pip install --pre torch torchvision --extra-index-url https://download.pytorch.org/whl/nightly/cu116
   if [ $? -eq 0 ];then