update to php 8.1

Dockerfile

@@ -1,4 +1,4 @@
-FROM php:7.4.7-cli-buster
+FROM php:8.1-cli-bookworm
 
 RUN apt-get update && apt-get install -y unzip
 RUN curl -sS https://getcomposer.org/installer | php -- --install-dir=/usr/local/bin --filename=composer