[docs]: JS Testing sdk package name wrong

### URL/Location

https://docs.aws.amazon.com/lambda/latest/dg/durable-testing.html

### Describe What's Incorrect or Lacking

```
npm install --save-dev @aws/aws-durable-execution-sdk-js-testing
```

### Suggested Improvement

actual link to download the package is
```
 npm install --save-dev @aws/durable-execution-sdk-js-testing
```

### Additional Context

_No response_