Is AWS boto (python) supporting SES signature version 4?

My recommendation is that you migrate from boto, which is essentially deprecated, to boto3 because boto3 supports signature v4 by default (with the exception of S3 pre-signed URLs which has to be explicitly configured).

Promoting j0nam1el's comment to an answer, as it directly answers the question:

I found where SignatureV4 support was added to boto (in 2012). However, cross-referencing this and this, it appears that the boto.ses code still uses HmacAuthV3Handler. From this, I conclude that users of the older 'boto.ses' library will not be able to continue utilizing AWS SES past 2020-10-01.