Update orchestra/testbench requirement from ^7.23|^8.3 to ^7.28.2

Updates the requirements on [orchestra/testbench](https://github.com/orchestral/testbench) to permit the latest version.
- [Release notes](https://github.com/orchestral/testbench/releases)
- [Changelog](https://github.com/orchestral/testbench/blob/develop/CHANGELOG-7.x.md)
- [Commits](https://github.com/orchestral/testbench/commits/v7.28.2)

---
updated-dependencies:
- dependency-name: orchestra/testbench
  dependency-type: direct:development
...

Signed-off-by: dependabot[bot] <[email protected]>

composer.json

@@ -30,7 +30,7 @@
     "require-dev": {
         "laravel/legacy-factories": "^1.1",
         "mockery/mockery": "^1.4",
-        "orchestra/testbench": "^7.23|^8.3",
+        "orchestra/testbench": "^7.28.2",
         "vimeo/psalm": "4.24.0"
     },
     "config": {