refactor: remove vestigial ALLOWED_URL_SCHEMES from package.py
refactor: remove vestigial ALLOWED_URL_SCHEMES from package.py

LLNL/spack,iulian787/spack,LLNL/spack,iulian787/spack,iulian787/spack,LLNL/spack,iulian787/spack,LLNL/spack,LLNL/spack,iulian787/spack