chore(zsh): install rbenv, pyenv and nodenv with zinit instead of brew

Main benefit is that these tools will now auto-install correctly on
Linux systems too.

Brewfile

@@ -44,13 +44,10 @@ brew 'node'
 brew 'pandoc'
 brew 'peco'
 brew 'pgformatter'
-brew 'pyenv'
-brew 'rbenv'
 brew 'rclone'
 brew 'readline'
 brew 'redis'
 brew 'ripgrep'
-brew 'ruby-build'
 brew 'rustup-init'
 brew 'shellcheck'
 brew 'source-highlight'
@@ -71,15 +68,6 @@ brew 'zsh'
 tap 'heroku/brew'
 brew 'heroku'
 
-# node.js version manager
-tap 'nodenv/nodenv'
-brew 'nodenv'
-brew 'node-build'
-brew 'nodenv-aliases'
-brew 'nodenv-each'
-brew 'nodenv-nvmrc'
-brew 'nodenv-package-rehash'
-
 # sshfs requires osxfuse
 cask 'osxfuse'
 brew 'sshfs'