git: fix grt on path with spaces

Fixes #7682

plugins/git/git.plugin.zsh

@@ -226,7 +226,7 @@ alias grmc='git rm --cached'
 alias grmv='git remote rename'
 alias grrm='git remote remove'
 alias grset='git remote set-url'
-alias grt='cd $(git rev-parse --show-toplevel || echo ".")'
+alias grt='cd "$(git rev-parse --show-toplevel || echo .)"'
 alias gru='git reset --'
 alias grup='git remote update'
 alias grv='git remote -v'