Change prompt arrow to non-multibyte character

The multibyte character does not play well with some terminal emulators like
putty - after tab completion the prompt start point is moved 2 characters to the
right.

zsh/omz-custom/cinaeco.zsh-theme

@@ -4,7 +4,7 @@ print -Pn "\e]1;`hostname | cut -d. -f1`\a"
 ## Multiline Prompt
 PROMPT='
 $(host_name)$(current_folder)$(git_prompt_info)$(background_job_info)
-%{$fg[magenta]%}%n → %{$reset_color%}'
+%{$fg[magenta]%}%n -> %{$reset_color%}'
 RPROMPT='$(vi_mode_prompt_info) %{$reset_color%}%T %{$fg[white]%}%h%{$reset_color%}'
 
 MODE_INDICATOR="%{$fg[green]%}vi-mode%{$reset_color%}"