chore(deps-dev): Update phpunit/phpunit requirement from 9.* to 10.*

Updates the requirements on [phpunit/phpunit](https://github.com/sebastianbergmann/phpunit) to permit the latest version.
- [Release notes](https://github.com/sebastianbergmann/phpunit/releases)
- [Changelog](https://github.com/sebastianbergmann/phpunit/blob/10.1.2/ChangeLog-10.1.md)
- [Commits](sebastianbergmann/phpunit@9.0.0...10.1.2)

---
updated-dependencies:
- dependency-name: phpunit/phpunit
  dependency-type: direct:development
...

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

composer.json

@@ -30,7 +30,7 @@
         "stripe/stripe-php": "10.*"
     },
     "require-dev": {
-        "phpunit/phpunit": "9.*",
+        "phpunit/phpunit": "10.*",
         "phpstan/phpstan": "1.*"
     },
     "scripts": {