Image copy to another region failed

### **This is autogenerated. Please review and update as needed.**

## Describe the bug

**Command Name**
`az image copy
Extension Name: image-copy-extension. Version: 0.2.8.`

**Errors:**
```
...
subprocess.py, ln 438, in run
subprocess.CalledProcessError: Command '['C:\\Program Files (x86)\\Microsoft SDKs\\Azure\\CLI2\\python.exe', '-m', 'azure.cli', 'snapshot', 'create', '--name', 'RG2021RH77-image-v2_os_disk_snapshot', '--location', 'westus', '--resource-group', 'MSCAzurePOCRG', '--source', '/subscriptions/146ea064-4d31-4a0e-95f2-c4226eb2ec0d/resourceGroups/MSCAzurePOCRG/providers/Microsoft.Compute/disks/RG2021rhtest_disk1_33f7e7c6948b40ca84b433a609678ad4', '--output', 'json', '--tags', 'created_by=image-copy-extension']' returned non-zero exit status 3.
```

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

- _Put any pre-requisite steps here..._
- `az image copy --source-resource-group {} --source-object-name {} --target-location {} --target-resource-group {} --cleanup`

## Expected Behavior

## Environment Summary
```
Windows-10-10.0.17763-SP0
Python 3.6.8
Installer: MSI

azure-cli 2.21.0

Extensions:
image-copy-extension 0.2.8

```
## Additional Context