feat(lib)!: soft-deprecate `upgrade_oh_my_zsh` function for everybody

BREAKING CHANGE: the `upgrade_oh_my_zsh` function now calls `omz update` directly.

lib/functions.zsh

@@ -9,23 +9,8 @@ function uninstall_oh_my_zsh() {
 }
 
 function upgrade_oh_my_zsh() {
-  if (( $+functions[_omz::update] )); then
   echo >&2 "${fg[yellow]}Note: \`$0\` is deprecated. Use \`omz update\` instead.$reset_color"
-  fi
-
-  # Run update script
-  env ZSH="$ZSH" zsh -f "$ZSH/tools/upgrade.sh" --interactive
-  local ret=$?
-  # Update last updated file
-  zmodload zsh/datetime
-  echo "LAST_EPOCH=$(( EPOCHSECONDS / 60 / 60 / 24 ))" >! "${ZSH_CACHE_DIR}/.zsh-update"
-  # Remove update lock if it exists
-  command rm -rf "$ZSH/log/update.lock"
-  # Restart the zsh session
-  if [[ $ret -eq 0 ]]; then
-    # Check whether to run a login shell
-    [[ "$ZSH_ARGZERO" = -* ]] && exec -l "${ZSH_ARGZERO#-}" || exec "$ZSH_ARGZERO"
-  fi
+  omz update
 }
 
 function take() {