[SETUP]: Bump php from 8.1.11-fpm to 8.1.12-fpm in /docker/app/php8.1

Bumps php from 8.1.11-fpm to 8.1.12-fpm.

---
updated-dependencies:
- dependency-name: php
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

docker/app/php8.1/Dockerfile

@@ -1,4 +1,4 @@
-FROM php:8.1.11-fpm
+FROM php:8.1.12-fpm
 
 ARG USER_ID
 ARG GROUP_ID