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 198 to 199.
- [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/v198...v199)

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

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

tests/apps/php/composer.lock

@@ -1000,16 +1000,16 @@
     "packages-dev": [
         {
             "name": "heroku/heroku-buildpack-php",
-            "version": "v198",
+            "version": "v199",
             "source": {
                 "type": "git",
                 "url": "https://github.com/heroku/heroku-buildpack-php.git",
-                "reference": "043613ce119387da7e04b2ba8db00fe12ab0b55c"
+                "reference": "1a4e5d3ffe128f8eb8a17e50616462d3c804e11f"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/heroku/heroku-buildpack-php/zipball/043613ce119387da7e04b2ba8db00fe12ab0b55c",
-                "reference": "043613ce119387da7e04b2ba8db00fe12ab0b55c",
+                "url": "https://api.github.com/repos/heroku/heroku-buildpack-php/zipball/1a4e5d3ffe128f8eb8a17e50616462d3c804e11f",
+                "reference": "1a4e5d3ffe128f8eb8a17e50616462d3c804e11f",
                 "shasum": ""
             },
             "bin": [
@@ -1037,7 +1037,7 @@
                 "nginx",
                 "php"
             ],
-            "time": "2021-09-28T23:39:37+00:00"
+            "time": "2021-10-08T15:04:20+00:00"
         }
     ],
     "aliases": [],