Update orchestra/testbench requirement from ^7.24 to ^8.12

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-8.x.md)
- [Commits](orchestral/testbench@v7.24.0...v8.12.1)

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

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

composer.json

@@ -25,7 +25,7 @@
   },
   "require-dev": {
     "mockery/mockery": "^1.4.3",
-    "orchestra/testbench": "^7.24",
+    "orchestra/testbench": "^8.12",
     "phpunit/phpunit": "^9.5.4"
   },
   "autoload-dev": {