az devops security group membership list --relationship memberof returns invalid json

Hi,

Using the membership list --relationship memberof option, but I believe the 'members' option does the same, I come across the issue that powershell cannot convert the output from json.

Code: $MemberOf = (az devops security group membership list --id $GroupId --relationship memberof) | ConvertFrom-Json

In our case I see three groups returned, but the $MemberOf only holds one object, not three. Even if I force the output in Json format.

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* ID: 52ec4f1d-e2b6-2397-ea6f-d8ceb8a3b315
* Version Independent ID: 58fbf7ef-2e9f-d56f-3e75-d37195202350
* Content: [az devops security group membership](https://docs.microsoft.com/en-us/cli/azure/ext/azure-devops/devops/security/group/membership?view=azure-cli-latest)
* Content Source: [latest/docs-ref-autogen/ext/azure-devops/devops/security/group/membership.yml](https://github.com/MicrosoftDocs/azure-docs-cli/blob/live/latest/docs-ref-autogen/ext/azure-devops/devops/security/group/membership.yml)
* GitHub Login: @rloutlaw
* Microsoft Alias: **routlaw**