[windows] skip 'UNIX only'

# test that chezmoi apply with a scriptTempDir set creates a temporary directory
expandenv $CHEZMOICONFIGDIR/chezmoi.toml
chezmoi apply
stdout ok
exists $WORK/script-tmp

-- home/user/.config/chezmoi/chezmoi.toml --
scriptTempDir = "$WORK/script-tmp"
-- home/user/.local/share/chezmoi/run_script.sh --
#!/bin/sh

echo ok
