fix(dockerfile): switch v1 to ECR to avoid Docker Hub rate limits

Change base image from docker.io/library/php to public.ecr.aws/docker/library/php
to avoid Docker Hub's unauthenticated pull rate limits (100 pulls per 6 hours).

AWS ECR Public Gallery has no rate limits for public images and is a reliable
mirror for Docker Hub's official images. This matches the approach already used
in Dockerfile.v2.

Fixes: 'toomanyrequests: You have reached your unauthenticated pull rate limit'

Author: KingPin

Dockerfile.v1

@@ -1,5 +1,5 @@
 ARG VERSION=8.3-cli-alpine
-FROM php:${VERSION}
+FROM public.ecr.aws/docker/library/php:${VERSION}
 ARG PHPVERSION
 ARG BASEOS