fix(colorize): check if $ZSH_COLORIZE_TOOL exists (#11325)

plugins/colorize/colorize.plugin.zsh

@@ -23,7 +23,7 @@ colorize_check_requirements() {
     if [[ ${available_tools[(Ie)$ZSH_COLORIZE_TOOL]} -eq 0 ]]; then
         echo "ZSH_COLORIZE_TOOL '$ZSH_COLORIZE_TOOL' not recognized. Available options are 'pygmentize' and 'chroma'." >&2
         return 1
-    elif (( $+commands["$ZSH_COLORIZE_TOOL"] )); then
+    elif ! (( $+commands[$ZSH_COLORIZE_TOOL] )); then
         echo "Package '$ZSH_COLORIZE_TOOL' is not installed!" >&2
         return 1
     fi