bira: add virtualenv support in prompt

Fixes #7483
Closes #4973

themes/bira.zsh-theme

@@ -20,11 +20,14 @@ else
   fi
 fi
 local git_branch='$(git_prompt_info)%{$reset_color%}'
+local venv_prompt='$(virtualenv_prompt_info)%{$reset_color%}'
 
-PROMPT="╭─${user_host} ${current_dir} ${rvm_ruby} ${git_branch}
+PROMPT="╭─${venv_prompt} ${user_host} ${current_dir} ${rvm_ruby} ${git_branch}
 ╰─%B${user_symbol}%b "
 RPS1="%B${return_code}%b"
 
 ZSH_THEME_GIT_PROMPT_PREFIX="%{$fg[yellow]%}‹"
 ZSH_THEME_GIT_PROMPT_SUFFIX="› %{$reset_color%}"
 
+ZSH_THEME_VIRTUAL_ENV_PROMPT_PREFIX="%{$fg[green]%}‹"
+ZSH_THEME_VIRTUAL_ENV_PROMPT_SUFFIX="› %{$reset_color%}"