free up disk space on Github runner

While building OpenSpace on a github action, the github runner was running out of disk space. Fortunately, there is an action to clear up disk space - 

    - name: Free Disk Space (Ubuntu)

      uses: jlumbroso/free-disk-space@main

      with:

        # this might remove tools that are actually needed,

        # if set to "true" but frees about 6 GB

        tool-cache: false

        

        # all of these default to true, but feel free to set to

        # "false" if necessary for your workflow

        android: true

        dotnet: true

        haskell: true

        large-packages: false

        docker-images: true

        swap-storage: false

Here, true means remove. Since we need some of the large packages and we do need the swap space, I set those to false, and that solved the problem.