Issues with FunctionsFramework::cloudEvent()

Having issues with FunctionsFramework::cloudEvent() when running in Cloud Functions (but not locally) as documented at https://cloud.google.com/functions/docs/tutorials/pubsub#preparing_the_application.

I'm calling the following:

```php
FunctionsFramework::cloudEvent('eventarc-event-name', 'myFunctionName');

function myFunctionName(\CloudEvents\V1\CloudEventInterface $event)
```

This runs locally, but when I run it on Cloud Run the it tells me I have to hint Google\CloudFunctions\CloudEvent, but if I do that it wants CloudEventInterface instead. Putting either results in the other being required.

```
PHP message: PHP Fatal error: Uncaught LogicException: Your function must have "Google\CloudFunctions\CloudEvent" as the typehint for the first argument in /workspace/vendor/google/cloud-functions-framework/src/CloudEventFunctionWrapper.php:65
```

I can't repeat this locally. FunctionsFramework calls the following, which locally always forces CloudEventInterface, and I can debug this right through to the Reflection check on line 71 of CloudEventFunctionWrapper

```php
public static function cloudEvent(string $name, callable $fn)
{
Invoker::registerFunction($name, new CloudEventFunctionWrapper($fn, true));
}
```

If I do both (which seems probably unintended and wrong anyway), I get the following error:

```
PHP message: PHP Fatal error: Uncaught Error: Call to undefined method ReflectionUnionType::getName() in /workspace/vendor/google/cloud-functions-framework/src/CloudEventFunctionWrapper.php:75 Stack trace: #0 /workspace/vendor/google/cloud-functions-framework/src/FunctionValidationTrait.php(43): Google\CloudFunctions\CloudEventFunctionWrapper->validateFirstParameter(Object(ReflectionParameter)) #1 /workspace/vendor/google/cloud-functions-framework/src/CloudEventFunctionWrapper.php(58): Google\CloudFunctions\CloudEventFunctionWrapper->validateFunctionSignature(Object(ReflectionFunction)) #2 /workspace/vendor/google/cloud-functions-framework/src/FunctionsFramework.php(35): Google\CloudFunctions\CloudEventFunctionWrapper->__construct('dicomwebImport', true) #3 /workspace/index.php(11): Google\CloudFunctions\FunctionsFramework::cloudEvent('transport-reque...', 'dicomwebImport') #4 /workspace/vendor/google/cloud-functions-framework/router.php(37): require_once('/workspace/inde...')
```

I'm not even sure how to proceed here, as this is the officially documented approach, but doesn't appear in the readme for this project at all.

Beginne mit CloudEventFunctionWrapper.php bei den Validierungsprüfungen um die Zeilen 65–75 und FunctionsFramework::cloudEvent(), und vergleiche anschließend die dokumentierte Signatur mit dem hier beschriebenen Verhalten von Cloud Run und der lokalen Umgebung. Reproduziere die Type-Hint-Validierung und den ReflectionUnionType-Fehler; abgeschlossen ist die Aufgabe, wenn die dokumentierte CloudEvent-Funktionssignatur in beiden Umgebungen konsistent behandelt wird.

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