fix(chruby): update brew sourcing for Apple Silicon (#12941)

Co-authored-by: Carlo Sala <carlosalag@protonmail.com>

plugins/chruby/chruby.plugin.zsh

@@ -22,6 +22,8 @@ _source-from-homebrew() {
   # check default brew prefix
   if [[ -h /usr/local/opt/chruby ]];then
     _brew_prefix="/usr/local/opt/chruby"
+  elif [[ -h /opt/homebrew/opt/chruby ]]; then
+    _brew_prefix="/opt/homebrew/opt/chruby"
   else
     # ok , it is not default prefix
     # this call to brew is expensive ( about 400 ms ), so at least let's make it only once