Update orchestra/testbench-core requirement from ^7.14 to ^7.39

Updates the requirements on [orchestra/testbench-core](https://github.com/orchestral/testbench-core) to permit the latest version.
- [Release notes](https://github.com/orchestral/testbench-core/releases)
- [Changelog](https://github.com/orchestral/testbench-core/blob/8.x/CHANGELOG-7.x.md)
- [Commits](orchestral/testbench-core@v7.14.0...v7.39.0)

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

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

composer.json

@@ -30,7 +30,7 @@
     },
     "require-dev": {
         "orchestra/testbench": "^7.14",
-        "orchestra/testbench-core": "^7.14",
+        "orchestra/testbench-core": "^7.39",
         "phpunit/phpunit": "^9.5.21",
         "vimeo/psalm": "4.24.0"
     },