[DocumentIntelligence] JSON error when calling begin_analyze_document

- **Package Name**: azure_ai_documentintelligence
- **Package Version**: 1.0.2
- **Operating System**: Win 11
- **Python Version**: 3.9

**Describe the bug**
Reading a PDF document triggers the following error:
**JSONDecodeError: Expecting value**

Though, the code is taken from the documentation. I precise that the code is not run on Azure but locally on a Windows system.

**To Reproduce**
```
from azure.core.credentials import AzureKeyCredential
from azure.ai.documentintelligence import DocumentIntelligenceClient

endpoint = "***"
key = "***"

client = DocumentIntelligenceClient(endpoint=endpoint, credential=AzureKeyCredential(key))

with open("my_file.pdf", "rb") as f:
poller = client.begin_analyze_document("prebuilt-read", body=f)
```
**Expected behavior**
I expect the code to run properly.