sz: fix fetch url for SZ for older releases (#19215)
sz: fix fetch url for SZ for older releases (#19215)

fixes #19213
LLNL/spack,LLNL/spack,LLNL/spack,LLNL/spack,iulian787/spack,iulian787/spack,LLNL/spack,iulian787/spack,iulian787/spack,iulian787/spack