Added get_tags() support for subscriptions.

[bertneef]

Just a very simple change, I wanted to get tags defined at the subscription level. Works like a charm in my test environment, it gets subscription level tags just as it would resource group or resource level tags.

[ghost]

Thank you for your submission, we really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.

❌ bertneef sign now
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[hongooi73]

Belated thanks! I'm not sure if the CLA link still works, but you might want to sign it just in case.