refactor: Do not rebuild alpine v3.16 base image for PHP 8.1

as the alpine image is not really updated and the build fails due to
missing old packages, we do not rebuild the alpine 3.16 image anymore
and use the base image already present in the registry

Author: aragon999

.github/workflows/build-docker-images.yaml

@@ -18,9 +18,6 @@ jobs:
       fail-fast: false
       matrix:
         include:
-          - php-version: "8.1"
-            flavour: alpine
-            distribution-version: "3.16"
           - php-version: "8.3"
             flavour: alpine
             distribution-version: "3.19"