Azure-arm builder : azure_tags format (HCL)

I have a JSON config that will build images in Azure using the azure-arm builder. I converted it to HCL format using the conversion tool. In my config I am adding a tag that stores the date that the image was built, and in the conversion it got converted to the below value. However, when trying to run a build with the updated HCL config, it fails with the below error.

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azure_tags = {
date = “${local.timestamp}”
gitsha = “123456”
}

*Expected a comma to mark the beginning of the next item.*

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I’ve tried various different formats with no success, so for now I’ve removed the date field and then it works fine. What is the proper format for adding in a variable into this particular map?