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 219 to 220.
- [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/v219...v220)

---
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

@@ -1001,16 +1001,16 @@
     "packages-dev": [
         {
             "name": "heroku/heroku-buildpack-php",
-            "version": "v219",
+            "version": "v220",
             "source": {
                 "type": "git",
                 "url": "https://github.com/heroku/heroku-buildpack-php.git",
-                "reference": "9acc2e638f02b7249b51225acb03fb7a7259f447"
+                "reference": "af0935921c10dc7d2d2f41b06c0a66c89102d8dd"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/heroku/heroku-buildpack-php/zipball/9acc2e638f02b7249b51225acb03fb7a7259f447",
-                "reference": "9acc2e638f02b7249b51225acb03fb7a7259f447",
+                "url": "https://api.github.com/repos/heroku/heroku-buildpack-php/zipball/af0935921c10dc7d2d2f41b06c0a66c89102d8dd",
+                "reference": "af0935921c10dc7d2d2f41b06c0a66c89102d8dd",
                 "shasum": ""
             },
             "bin": [
@@ -1038,7 +1038,7 @@
                 "nginx",
                 "php"
             ],
-            "time": "2022-06-09T21:04:15+00:00"
+            "time": "2022-06-15T15:34:32+00:00"
         }
     ],
     "aliases": [],