Bump php from 8.3.8 to 8.3.9 in /docker/php

Bumps php from 8.3.8 to 8.3.9.

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

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

docker/php/Dockerfile

@@ -1,4 +1,4 @@
-FROM php:8.3.8
+FROM php:8.3.9
 COPY --from=composer:2.7.7 /usr/bin/composer /usr/bin/composer
 
 # PECL for code coverage