Re-remove compatible-architectures setting as it's not supported in af-south-1

[estolfo]

af-south-1 doesn't support compatible-architectures.
We encountered this error before so removed it in #112
But then we erroneously added it back in #141
We then get this error when trying to publish the ARNs CompatibleArchitectures are not supported in af-south-1.

This PR removes the compatible-architectures option again.

[ghost]

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• Start Time: 2022-03-09T12:57:06.140+0000

• Duration: 6 min 11 sec

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[trentm]

Ah, sorry for causing that breakage.

So I understand: We could make it so we set --compatible-architectures ... in regions that do support it, right? Not suggesting we need to do that now.