%pyproject_install: Add --no-warn-script-location
    
    Otherwise you see:
    
        WARNING: The scripts py.test and pytest are installed in '/builddir/build/BUILDROOT/pytest-4.6.4-1.fc31.x86_64/usr/bin' which is not on PATH.
          Consider adding this directory to PATH or, if you prefer to suppress this warning, use --no-warn-script-location.
    
    And that is not relevant for us.