[MINOR] Move Package Dependencies for Python Testing

[christinadionysio]

This commit divides the installation of packages into a part that installs all generally needed packages and one part that is only installed for specific test runs like Scuro. Additionally, torch hub get's cached which reduces setup time.

[Baunsgaard]

LGTM, feel free to merge.

[Baunsgaard]

it would be good to additionally cache the datasets you use, see:

    - name: Cache Datasets
      uses: actions/cache@v4
      with:
        path: |
          src/main/python/systemds/examples/tutorials/mnist
          src/main/python/systemds/examples/tutorials/adult/data.zip
        key: ${{ runner.os }}-mnist-${{ hashFiles('src/main/python/systemds/examples/tutorials/mnist.py') }}-${{ hashFiles('src/main/python/systemds/examples/tutorials/adult.py') }}