build: add railpack.json with php-mysql and php-pdo apt packages

Dockerfile

@@ -1,3 +1,4 @@
 FROM php:8.2-apache
 RUN docker-php-ext-install pdo pdo_mysql mysqli
 RUN a2enmod rewrite
+

railpack.json

@@ -0,0 +1,7 @@
+{
+  "provider": "php",
+  "aptPackages": [
+    "php-mysql",
+    "php-pdo"
+  ]
+}