Executing `az ad user update` fails.

## Describe the bug

Executing `az ad user update` fails.
Additionally using `--debug` confirms that the request headers don't contain the required `Content-Type` header:
```log
cli.azure.cli.core.util: Request headers:
cli.azure.cli.core.util: 'User-Agent': 'python/3.10.8 (macOS-12.6.1-x86_64-i386-64bit) AZURECLI/2.42.0 (HOMEBREW)'
cli.azure.cli.core.util: 'Accept-Encoding': 'gzip, deflate'
cli.azure.cli.core.util: 'Accept': '*/*'
cli.azure.cli.core.util: 'Connection': 'keep-alive'
cli.azure.cli.core.util: 'x-ms-client-request-id': '955d0976-4c21-4fdb-b154-fe5592b76aed'
cli.azure.cli.core.util: 'CommandName': 'ad user update'
cli.azure.cli.core.util: 'ParameterSetName': '--id --debug'
cli.azure.cli.core.util: 'Authorization': 'Bearer eyJ0eXAiOiJKV...'
cli.azure.cli.core.util: 'Content-Length': '0'
```

**Command Name**
`az ad user update`

**Errors:**
```
Write requests (excluding DELETE) must contain the Content-Type header declaration.

```

## To Reproduce:
Steps to reproduce the behavior. Note that argument values have been redacted, as they may contain sensitive information.

- `az ad user update --id {} --debug`

## Expected Behavior
- It should not fail.

## Environment Summary
```
macOS-12.6.1-x86_64-i386-64bit, Darwin 21.6.0
Python 3.10.8
Installer: HOMEBREW

azure-cli 2.42.0

Extensions:
account 0.2.3

Dependencies:
msal 1.20.0
azure-mgmt-resource 21.1.0b1
```
## Additional Context