feat: remove zsh dependency

[matteo-cristino]

TODO: update documentation

[jaromil]

ohhh long due, well done!

[matteo-cristino]

I still see:

test/crypto_json/run.sh
1:#!/usr/bin/env zsh

test/crypto_ecdh/run.sh
1:#!/usr/bin/env zsh

build/publish_javascript.sh
1:#!/usr/bin/env zsh

build/zip-binaries.sh
1:#!/usr/bin/env zsh

docs/_media/scripts/parse_zencode.sh
1:#!/usr/bin/env zsh

docs/examples/zencode_coconut/run_coconut_example.sh
1:#!/usr/bin/env zsh

docs/examples/zencode_coconut/run_petition_example.sh
1:#!/usr/bin/env zsh

Should we update all of them too?