Minor cosmetic fix to minimal theme

Set the closing square-brace's FG colour to white, to match the opening brace, when the repo directory is dirty.

themes/minimal.zsh-theme

 ZSH_THEME_GIT_PROMPT_PREFIX="%{$reset_color%}%{$fg[white]%}["
 ZSH_THEME_GIT_PROMPT_SUFFIX=""
-ZSH_THEME_GIT_PROMPT_DIRTY="%{$fg[red]%}●%{$reset_color%}]%{$reset_color%} "
+ZSH_THEME_GIT_PROMPT_DIRTY="%{$fg[red]%}●%{$fg[white]%}]%{$reset_color%} "
 ZSH_THEME_GIT_PROMPT_CLEAN="]%{$reset_color%} "
 ZSH_THEME_SVN_PROMPT_PREFIX=$ZSH_THEME_GIT_PROMPT_PREFIX
 ZSH_THEME_SVN_PROMPT_SUFFIX=$ZSH_THEME_GIT_PROMPT_SUFFIX