[TASK] Use php8.1.0RC3-alpine as base image for core-testing-php81 image
PHP 8.1 RC3 was released and public php docker images was updated, this patch follow up this to update the used php8.1 version.
PHP 8.1 RC3 was released and public php docker images was updated, this patch follow up this to update the used php8.1 version.