Updated installer module copyright (#15138)
Updated installer module copyright (#15138)

Update the copyright for `installer.py`.
LLNL/spack,iulian787/spack,LLNL/spack,iulian787/spack,LLNL/spack,LLNL/spack,iulian787/spack,iulian787/spack,iulian787/spack,LLNL/spack