test(pest): update pestphp version and rename function

- Update `pestphp/pest` version from `^3.0` to `^3.1`.
- Rename function `clear_name_namespace` to `clear_same_namespace` for clarity.
- Modify the implementation of `clear_same_namespace` to overwrite PHP files instead of deleting them.

composer.json

@@ -37,7 +37,7 @@
         "fakerphp/faker": "^1.23",
         "guanguans/ai-commit": "dev-main",
         "mockery/mockery": "^1.6",
-        "pestphp/pest": "^3.0",
+        "pestphp/pest": "^3.1",
         "phpstan/extension-installer": "^1.4",
         "phpstan/phpstan": "^1.12",
         "rector/rector": "^1.2",