Upgrade Swoosh dependency
Newer version of Swoosh ships a useful adapter ExAwsAmazonSES, which wraps AmazonSES to use dynamic credentials fetched from IAM role. This is particular useful if Pleroma is running in an AWS environment.
Currently the OTP release of Pleroma ships Swoosh 1.3.11, which does not include this adapter. Please consider upgrading Swoosh to a newer version.