install torch via pip in workflow

Author: LarsKue

.github/workflows/tests.yaml

@@ -85,7 +85,7 @@ jobs:
       - name: Install PyTorch
         if: ${{ matrix.backend == 'torch' }}
         run: |
-          conda install pytorch torchvision torchaudio cpuonly -c pytorch
+          pip install torch torchvision torchaudio --index-url https://download.pytorch.org/whl/cpu
 
       - name: Show Environment Info
         run: |