sbang: use utf-8 for encoding when patching (#13490)
sbang: use utf-8 for encoding when patching (#13490)

This fixes a UnicodeDecodeError in the sbang patching function.
LLNL/spack,LLNL/spack,iulian787/spack,LLNL/spack,LLNL/spack,iulian787/spack,iulian787/spack,LLNL/spack,iulian787/spack,iulian787/spack