[Docker] Ensure release and test builds pull fresh PHP base images #674

Affected Version

2026.3

Affected capability

Other

Steps to reproduce

In pimcore/docker, the release and test workflows build images without
--pull, and the release workflow resolves PHP_VERSION using docker run
without --pull=always.

When an older PHP base image is cached locally and its registry tag has
been updated, these commands can reuse the cached image.

This concerns Docker build workflows, independently of the installed
Pimcore application version.

Tracking issue for the existing fix:
pimcore/docker#267

Actual Behavior

Builds do not explicitly require refreshing the PHP base image.
If an outdated image is cached locally, upstream patch updates may
not be picked up.

This is a cache-dependent behavior; it does not establish that current
published Pimcore images are outdated.

Expected Behavior

Always pull the current PHP base image when resolving its patch version
and building release and test images.

Preserve the existing PHP series, image tags and build matrix.