Update dump.sh

[Inmovilizame]

dot package dump shows an error while dumping npm packages due to the change on default homebrew prefix on M1 Macs.

 dot package
package dump
 > Brew apps dumped on /Users/roi/.dotfiles/os/mac/brew/Brewfile
 > Python apps dumped on /Users/roi/.dotfiles/langs/python/requirements.txt
ls: /usr/local/lib/node_modules: No such file or directory

Changing hardcoded path to use $HOMEBREW_PREFIX env var solves the problem