refactor: update PHP to 8.2

fix: possible division by 0 on statistics page
fix: duplicated messages on discord notifications
docs: update readme

Dockerfile

@@ -1,5 +1,5 @@
 # Use the php:8.0.5-fpm-alpine base image
-FROM php:8.0.5-fpm-alpine
+FROM php:8.2-fpm-alpine
 
 # Set working directory to /var/www/html
 WORKDIR /var/www/html