feat(agnoster): add git tag to prompt (#8417)

Co-authored-by: Jakub Novotny <jakub.novotny@deutsche-boerse.com>

themes/agnoster.zsh-theme

@@ -109,7 +109,9 @@ prompt_git() {
    if [[ "$(git rev-parse --is-inside-work-tree 2>/dev/null)" = "true" ]]; then
     repo_path=$(git rev-parse --git-dir 2>/dev/null)
     dirty=$(parse_git_dirty)
-    ref=$(git symbolic-ref HEAD 2> /dev/null) || ref="➦ $(git rev-parse --short HEAD 2> /dev/null)"
+    ref=$(git symbolic-ref HEAD 2> /dev/null) || \
+    ref="◈ $(git describe --exact-match --tags HEAD 2> /dev/null)" || \
+    ref="➦ $(git rev-parse --short HEAD 2> /dev/null)" 
     if [[ -n $dirty ]]; then
       prompt_segment yellow black
     else