golang SDK for using SES, trying to move to signature v4, getting exception

Hi all,

My golang application is currently sending emails via the aws go SDK (ses package, although I tried sesv2 and got the same results!), very similar to the example provided here:
https://docs.aws.amazon.com/ses/latest/DeveloperGuide/examples-send-using-sdk.html

Changed the credentials (key and secret) to v4, and I'm getting signature exceptions.
Am I supposed to change the golang code that's sending the emails to do some different to support this v4 signature?