chore(deps): update php docker tag to v8.1.28 (#164)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

renovate.Dockerfile

@@ -8,7 +8,7 @@ FROM scratch
 
 # EOL: 2024-11-25
 # renovate: datasource=docker depName=php versioning=docker
-ENV PHP_VERSION=8.1.27
+ENV PHP_VERSION=8.1.28
 
 # EOL: 2025-12-08
 # renovate: datasource=docker depName=php versioning=docker