chore(deps-dev): bump heroku/heroku-buildpack-php in /tests/apps/php

Bumps [heroku/heroku-buildpack-php](https://github.com/heroku/heroku-buildpack-php) from 299 to 300.
- [Release notes](https://github.com/heroku/heroku-buildpack-php/releases)
- [Changelog](https://github.com/heroku/heroku-buildpack-php/blob/main/CHANGELOG.md)
- [Commits](https://github.com/heroku/heroku-buildpack-php/compare/v299...v300)

---
updated-dependencies:
- dependency-name: heroku/heroku-buildpack-php
  dependency-version: '300'
  dependency-type: direct:development
  update-type: version-update:semver-major
...

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

tests/apps/php/composer.lock

@@ -605,16 +605,16 @@
     "packages-dev": [
         {
             "name": "heroku/heroku-buildpack-php",
-            "version": "v299",
+            "version": "v300",
             "source": {
                 "type": "git",
                 "url": "https://github.com/heroku/heroku-buildpack-php.git",
-                "reference": "207f07a27f4644d0cf349febe88219d53695f57d"
+                "reference": "b52841c0eea8c9dadf4d7dc4dc0736d4ee3d2b29"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/heroku/heroku-buildpack-php/zipball/207f07a27f4644d0cf349febe88219d53695f57d",
-                "reference": "207f07a27f4644d0cf349febe88219d53695f57d",
+                "url": "https://api.github.com/repos/heroku/heroku-buildpack-php/zipball/b52841c0eea8c9dadf4d7dc4dc0736d4ee3d2b29",
+                "reference": "b52841c0eea8c9dadf4d7dc4dc0736d4ee3d2b29",
                 "shasum": ""
             },
             "bin": [
@@ -644,9 +644,9 @@
             ],
             "support": {
                 "issues": "https://github.com/heroku/heroku-buildpack-php/issues",
-                "source": "https://github.com/heroku/heroku-buildpack-php/tree/v299"
+                "source": "https://github.com/heroku/heroku-buildpack-php/tree/v300"
             },
-            "time": "2026-10-22T18:15:48+00:00"
+            "time": "2026-10-29T18:03:00+00:00"
         }
     ],
     "aliases": [],