Explicitly install torch cpu in SHARK CI

.github/workflows/test_shark.yml

@@ -49,6 +49,7 @@ jobs:
           cd $GITHUB_WORKSPACE/SHARK
           python${{ matrix.version }} -m venv shark.venv
           source shark.venv/bin/activate
+          pip install --pre torch torchvision --index-url https://download.pytorch.org/whl/nightly/cpu
           pip install -r requirements.txt --no-cache-dir
           pip install -e .
           python apps/shark_studio/tests/api_test.py